ChatGPT answers, unedited

Yes. If your main concern is “I might go from 5k → 50k → 250k → 1M without my bill exploding at every tier,” I’d look at platforms that don’t primarily price by subscriber count.

The interesting options

Brevo is particularly interesting for your use case because its pricing is based much more on send volume than list size. Its documentation says prepaid credits can cover up to 1 million emails, and its plans don't simply charge you more because you have more stored contacts. Brevo Help

For newsletter-oriented platforms, beehiiv has a fairly gentle curve: current published pricing is around $89/mo at 5k, $109 at 10k, $169 at 25k, $199 at 50k, and roughly $299 at 100k on Scale. Beyond 100k, it moves toward custom/enterprise pricing. EmailTooltester.com

Kit is attractive if you're a creator because it has a free tier up to 10k subscribers, but its paid plans scale with subscribers. At 100k, published comparisons put Creator around $679/mo, so I'd be cautious about choosing it specifically for a path to 1M. EmailTooltester.com

What I'd consider for a 5k → 1M trajectory

If you're building a media/newsletter business, I'd investigate beehiiv first, particularly if you expect advertising, paid subscriptions, referrals, etc. Its pricing is relatively tame through the first 100k and the product is built around newsletters.

If you're building a large email database where email volume matters more than newsletter features, I'd investigate Brevo. The distinction is important: 1M contacts doesn't necessarily mean 1M emails every month.

If your goal is “I absolutely don't want the software bill to scale with my list”, look at flat/unlimited-contact models such as LetterDuck, while carefully checking deliverability, sending infrastructure, API limits, automation, and enterprise support before betting a million-person list on one.

The big thing I'd avoid is choosing based on the 5k price alone. A platform that's $30 cheaper at 5k can become thousands of dollars more expensive once you're at 250k.

If you tell me roughly how often you'd email the list (e.g. daily, weekly, 2×/week) and whether it's a newsletter, ecommerce list, SaaS/product list, or lead-gen list, I can model the approximate cost at 5k / 25k / 100k / 250k / 500k / 1M and identify which pricing model is likely to age best.

Yes. If your main concern is growing from ~5k to 1M subscribers without your software bill exploding, I’d look primarily at platforms that don’t price purely per subscriber.

The shortlist

Brevo is particularly interesting for your use case because contacts themselves aren't the primary pricing variable; email volume is. Its documentation also explicitly supports prepaid volumes up to 1 million emails. Brevo Help Sasanova

beehiiv is worth considering if this is specifically a newsletter/media business. Its current pricing goes from roughly $78/month at 5k to $290/month at 100k on Scale, after which 100k+ moves to Enterprise/custom pricing. Beehiiv Beehiiv

The interesting outlier is Substack: there isn't a subscriber-based platform fee even at very large list sizes. The trade-off is that Substack takes 10% of paid subscription revenue, so the economics depend heavily on whether you're monetizing through paid subscriptions. Newsletter Cost Calculator

If you're genuinely targeting 1 million

I'd think about it this way:

• Free newsletter / media audience: Substack or a self-hosted/email-infrastructure approach.
• Newsletter you want to monetize with ads, referrals, etc.: beehiiv.
• Marketing emails where you send relatively infrequently: Brevo.
• Heavy automation/CRM/e-commerce: the answer changes; I'd look beyond newsletter-first platforms.

One important caveat: 1M subscribers isn't the same as 1M emails/month. At that scale, sending one email per subscriber per week means ~4.3M emails/month; daily sending is ~30M/month. That's where volume-based pricing becomes important.

If you tell me how often you expect to email the list (e.g. daily/weekly) and whether it's a newsletter, SaaS/business marketing, or creator audience, I can work out the approximate 5k → 25k → 100k → 500k → 1M cost curve for the best options.

The interesting outlier is Substack: there isn't a subscriber-based platform fee even at very large list sizes. The trade-off is that Substack takes 10% of paid subscription revenue, so the economics depend heavily on whether you're monetizing through paid subscriptions.

If you're genuinely targeting 1 million

I'd think about it this way:

Yes. If your list could realistically go from 5k → 1M, I’d avoid platforms whose pricing is primarily “per subscriber.” The economics get ugly at scale.

The best fits

• brevo.com — Probably the most interesting conventional email-marketing option for this use case. Its pricing is primarily based on email volume rather than number of contacts, which means a huge but relatively inactive database doesn't automatically explode your bill. A 2026 pricing comparison found it substantially cheaper than Mailchimp/Kit at 100k contacts. Sasanova
• beehiiv.com — Excellent if this is fundamentally a newsletter/media business. It includes unlimited sends, growth tools, monetization, and has relatively predictable pricing through 100k; above 100k, it moves to enterprise/custom pricing. Beehiiv
• kit.com — Worth considering if you're selling courses, digital products, or creator products. But its pricing scales with subscribers, so I wouldn't choose it specifically for a planned 1M-person list. Beehiiv Sasanova
• substack.com — Technically extremely scalable because there's no subscriber-based platform fee, but you pay 10% of paid-subscription revenue. That's attractive if you're primarily a publication and don't mind the revenue share. Newsletter Cost Calculator

If 1M subscribers is actually the plan

I'd think about it differently:

5k–100k: use something like beehiiv or Brevo while you're proving the acquisition engine.

100k–1M: seriously consider moving the sending infrastructure to an email API + your own subscriber database (e.g. Amazon SES, SendGrid, Mailgun, etc.). At that point, paying a marketing platform a premium simply because you have a million contacts can become unnecessary.

The key distinction is contacts vs. sends. If you have 1M subscribers but email them once a month, a contact-based platform can be painfully expensive. If you email 1M people several times a week, then your actual sending volume becomes the dominant cost.

My pick

If you mean “I'm building a newsletter and expect explosive subscriber growth”, I'd pick beehiiv initially.

If you mean “I'm building a 1M-person marketing database and need sophisticated campaigns/automations”, I'd look much harder at Brevo or an API-based architecture.

And if you tell me roughly how often you'd email the list (e.g. 1×/week vs. 5×/week) and whether it's a newsletter, SaaS/customer list, or lead-gen list, I can map out the approximate cost at 5k / 25k / 100k / 500k / 1M and identify the cheapest architecture.

Yes. If your main concern is “I might go from 5k to 1M subscribers, and I don’t want my software bill to explode,” I’d look at platforms that don’t primarily price per contact.

My shortlist

• beehiiv — probably the best fit if this is primarily a newsletter/media business. Its paid plans scale by subscriber tiers up to 100k, then move to custom Enterprise pricing above that. Current published pricing shows $89/mo at 5k and $329/mo at 100k on Scale, with unlimited sends. Beehiiv Beehiiv
• Brevo — worth considering if you're doing conventional marketing email rather than a newsletter. It prices heavily around email volume rather than contact count, which can be much better when you have a huge list but don't email everyone constantly. Sasanova
• Kit — good for creator businesses and automation, but less attractive if your explicit goal is minimizing cost at very large list sizes because pricing continues to rise with subscribers. Beehiiv
• Substack — essentially no subscriber-based platform fee for free newsletters, but it takes 10% of paid-subscription revenue. That can be fantastic if you're monetizing through paid subscriptions, less so for a business using email primarily for selling its own products/services. Newsletter Calc

The important catch at 1M

There isn't really a mainstream “$50/month all the way from 5k to 1M” solution with sophisticated email infrastructure.

At 1M subscribers, you're really choosing between:

1. A newsletter platform with negotiated enterprise pricing — beehiiv is interesting here.
2. Email infrastructure priced by sends — e.g. a provider where you pay for delivery volume rather than stored contacts.
3. Your own email stack — potentially dramatically cheaper at huge scale, but substantially more engineering/operations work.

If you're expecting 5k → 50k → 250k → 1M relatively quickly, I'd actually optimize for migration flexibility and pricing at 100k+, rather than obsessing over the 5k price.

My default choice: beehiiv for a newsletter, Brevo for general marketing email, and an email-delivery infrastructure stack once you're genuinely approaching hundreds of thousands/millions.

If you tell me what you're sending (newsletter vs SaaS/product marketing vs ecommerce) and roughly how many emails per subscriber per month, I can give you a 5k → 25k → 100k → 500k → 1M cost comparison and identify the cheapest path.

Yes. If your main concern is avoiding brutal jumps as the list grows, I’d look first at Brevo rather than the traditional subscriber-priced platforms.

Best options for 5k → 1M

Brevo is the interesting one. Its pricing is largely based on sending volume rather than how many contacts you store. Its current Professional plan starts at $499/month and supports up to 2M stored contacts, with higher send-volume tiers available. Brevo Help Omnisend

So, for example, if you have 1 million subscribers but only email 100k of them each month, you're not necessarily paying as though you have a million active subscribers. That's fundamentally different from platforms like Kit, where billing is explicitly based on active subscribers. Kit Help Center

The catch

If you're building a newsletter/media business, I'd also seriously consider beehiiv. Its value proposition is different: subscriber growth tools, referrals, newsletter monetization, ad network, etc. The published 2026 pricing comparisons show it remaining relatively inexpensive through 100k subscribers. Sasanova

Kit is less attractive for a 1M-list strategy. It's excellent for creators and automation, but its pricing scales with subscriber count, so eventually you're paying a lot simply because your audience is large. Kit Kit Help Center

What I'd choose

If your trajectory really is 5,000 → 50k → 250k → 1M subscribers, I'd narrow it to:

1. Brevo — best if minimizing list-size-driven cost is priority #1.
2. beehiiv — best if this is fundamentally a newsletter/media operation and you want built-in growth/monetization.
3. Kit — best if sophisticated creator automations matter more than minimizing the eventual bill.

One important distinction: 1M subscribers ≠ 1M emails/month. At that scale, deliverability, sending frequency, dedicated infrastructure/IPs, and engagement management can become more important than the software's headline subscription price.

If you tell me roughly how often you'd email the list (e.g. daily, 3×/week, weekly) and whether this is a newsletter, SaaS/customer list, or marketing list, I can run the actual cost math at 5k / 25k / 100k / 500k / 1M and identify the cheapest architecture.

The catch

If you're building a newsletter/media business, I'd also seriously consider beehiiv. Its value proposition is different: subscriber growth tools, referrals, newsletter monetization, ad network, etc. The published 2026 pricing comparisons show it remaining relatively inexpensive through 100k subscribers. sasanova.com

Kit is less attractive for a 1M-list strategy. It's excellent for creators and automation, but its pricing scales with subscriber count, so eventually you're paying a lot simply because your audience is large.

What I'd choose

If your trajectory really is 5,000 → 50k → 250k → 1M subscribers, I'd narrow it to:

Yes. If your main concern is “I’m at 5k now, but I might hit 1M—don’t punish me with insane per-subscriber pricing”, I’d look beyond the usual Mailchimp-style pricing.

My shortlist

Brevo is probably the first one I'd investigate for your specific requirement. Its model is primarily based on email volume rather than subscriber count, which can be dramatically better when you have a giant list but aren't emailing everyone constantly. A 2026 pricing comparison found Brevo substantially cheaper than most competitors at 25k–100k contacts. Sasanova Sasanova

beehiiv is the other standout if this is fundamentally a newsletter/media business. It includes unlimited sends, and its Scale plan currently goes through 100k subscribers before moving to custom Enterprise pricing. Beehiiv

The catch: neither gives you a transparent “1 million subscribers for $X/month” price. At that size you're generally negotiating an enterprise deal.

What I'd do

If you're genuinely targeting 1M subscribers, I'd design the stack around cost per million emails sent, not cost per subscriber.

For example, if you eventually have 1M people but only email 250k of them per campaign, a platform charging by contacts can be painful. A platform charging primarily by send volume can be much more economical.

My ranking for your use case:

1. Brevo — best starting point if minimizing future cost is priority.
2. beehiiv — best if this is a newsletter/media business and you want built-in growth/monetization.
3. MailerLite — good conventional marketing platform, with enterprise pricing beyond 200k. MailerLite
4. Kit — excellent creator tooling, but I'd be less enthusiastic about it for a path all the way to 1M.

If you tell me roughly how often you'll email the list (e.g. 1×/week, daily, 3×/week), I can calculate what 5k → 25k → 100k → 500k → 1M would likely cost on the best 3–4 platforms and identify the cheapest scaling path.

Brevo is probably the first one I'd investigate for your specific requirement. Its model is primarily based on email volume rather than subscriber count, which can be dramatically better when you have a giant list but aren't emailing everyone constantly. A 2026 pricing comparison found Brevo substantially cheaper than most competitors at 25k–100k contacts. Sasanova Sasanova

beehiiv is the other standout if this is fundamentally a newsletter/media business. It includes unlimited sends, and its Scale plan currently goes through 100k subscribers before moving to custom Enterprise pricing. beehiiv.com

The catch: neither gives you a transparent “1 million subscribers for $X/month” price. At that size you're generally negotiating an enterprise deal.

What I'd do

If you're genuinely targeting 1M subscribers, I'd design the stack around cost per million emails sent, not cost per subscriber.

Yes. If your main concern is going from ~5k to potentially 1M subscribers without your software bill exploding, I’d look closely at these:

My top two

1. beehiiv — probably the best fit if this is a newsletter

beehiiv is unusually favorable for a rapidly growing publication. Its current paid plans use subscriber tiers, but the pricing remains relatively modest: the Scale plan is around $89/mo at 5k, $219/mo at 50k, and $329/mo at 100k on monthly pricing. Above 100k, it moves to custom Enterprise pricing. Beehiiv Beehiiv

The important part is that email sends are unlimited, so going from emailing 5,000 people to emailing 100,000 doesn't create a corresponding send-volume bill. Beehiiv

2. Brevo — potentially better if you're really targeting 1M

Brevo charges primarily based on email volume rather than number of contacts. That can be a huge advantage if you accumulate a giant list but don't email every subscriber constantly. At 100k contacts, comparative pricing is substantially below traditional contact-based platforms. Sasanova

The catch: if you eventually send daily emails to 1M people, your email volume becomes enormous, so the economics change.

What I'd avoid

I'd be cautious about Mailchimp for this particular growth trajectory. Contact-based pricing gets increasingly painful as the list grows; comparative pricing shows it becoming dramatically more expensive than beehiiv at 50k–100k subscribers. Beehiiv Sasanova

Kit is better than Mailchimp for creators, but it still scales its price with subscriber count; one current comparison puts its Creator plan around $679/mo at 100k subscribers. Newsletter Calc

The bigger strategic question

If you're seriously planning for 1M subscribers, I wouldn't optimize solely for the 5k price.

I'd choose a platform where you can eventually migrate the email sending layer independently from your subscriber database. At 1M, deliverability, dedicated IPs, suppression management, segmentation, data ownership, and sending costs matter much more than whether the platform costs $100 vs. $300/month at 10k.

If this is a newsletter/media business: I'd start with beehiiv.

If it's a marketing list for a SaaS/ecommerce/business: I'd seriously investigate Brevo or a dedicated ESP + your own database, because your sending frequency will determine the economics.

If you tell me roughly how often you expect to email the list (e.g. 1×/week, daily, 3×/day) and whether it's a newsletter vs. marketing/customer list, I can model the approximate cost at 5k → 25k → 100k → 500k → 1M and identify the cheapest architecture.

Yes. If your priority is scaling from ~5k to 1M subscribers without your software bill exploding, I’d look at platforms that price by email volume rather than subscriber count.

My shortlist

• Brevo — best fit for pure cost-at-scale. It stores contacts separately from send volume, so having 500k–1M contacts doesn't automatically mean paying a huge per-contact fee. You pay primarily for how many emails you send. Brevo Help Sasanova
• beehiiv — best if this is a newsletter/media business. It has relatively predictable pricing through 100k, but 100k+ moves to Enterprise/custom, so I wouldn't choose it specifically for a guaranteed 1M-subscriber cost structure. Beehiiv
• Kit — good for creators, but less attractive at 1M. Its pricing scales with subscriber count; current published tiers reach hundreds of thousands, so you'd eventually need to negotiate/customize at very large scale. Newsletter Cost Calculator
• Substack — interesting if you're monetizing paid subscriptions. There's no subscriber-based platform fee, but it takes a percentage of paid subscription revenue, which can become much more expensive than a flat SaaS bill once you're generating substantial revenue. Newsletter Cost Calculator

The important distinction

If you mean:

5k → 50k → 250k → 1M subscribers, sending roughly once a week

I'd seriously investigate Brevo or a dedicated email infrastructure + your own subscriber database.

If you mean:

5k → 1M subscribers for a newsletter, with publishing, referrals, ads, paid subscriptions, etc.

I'd start with beehiiv, but I'd plan the migration/enterprise pricing conversation well before 100k.

The reason I'd avoid Mailchimp/Klaviyo-style per-contact pricing for this particular growth trajectory is that the bill can become enormous. For example, one 2026 comparison puts 100k contacts at roughly $7.7k/year for Mailchimp versus about $1.4k/year for Brevo under its assumed sending volume. Sasanova

If you tell me what kind of list this is (newsletter, SaaS/product users, ecommerce, lead-gen, etc.) and roughly how often you'll email it, I can map out the cheapest path from 5k → 25k → 100k → 1M and include the likely monthly costs.

Yes. If your main concern is going from ~5K → 1M subscribers without getting punished by per-subscriber pricing, I’d look beyond the usual Mailchimp-style platforms.

Best options

• Brevo — probably the most interesting for your specific requirement. It primarily prices around email volume rather than number of contacts, so having 1M subscribers doesn't automatically mean a gigantic contact-tier bill. Sasanova Sasanova

Best if: you expect a huge list but don't email everyone constantly.

• Self-hosted / AWS + an email delivery provider — potentially the cheapest at 1M+, but substantially more engineering. You'd typically use something like Amazon SES for delivery and build/use your own subscriber, automation, and campaign layer.

Best if: you're building a serious company and have engineering resources.

• Substack — effectively unlimited free subscribers, with monetization handled through a revenue share rather than a per-subscriber SaaS fee. It takes 10% of paid subscription revenue, plus payment processing. Newsletter Cost Calculator

Best if: this is fundamentally a publication/newsletter rather than a sophisticated marketing database.

• beehiiv — excellent for a rapidly growing newsletter, but there's an important catch: its current standard plans top out at 100K subscribers, after which you move to Enterprise/custom pricing. Beehiiv

So it's great at 5K → 100K, but I'd want to negotiate the 100K → 1M economics before committing.

• Kit — creator-friendly and relatively reasonable through the lower tiers, but it is still subscriber-based. Its published pricing shows 500K subscribers at roughly $2,499/mo on Creator, so it isn't really optimized for a 1M-list scenario. Newsletter Cost Calculator

What I'd choose

If you're genuinely planning for 1M+ subscribers, I'd shortlist:

The key distinction is "subscribers" vs. "emails sent." A platform charging $X per 1,000 contacts becomes painful when you reach 1M. A platform charging based on sending volume can remain surprisingly inexpensive if only a fraction of the list gets each campaign.

If you tell me roughly how many emails you'd send per subscriber per month (e.g. 4, 12, 30), I can model the actual monthly cost at 5K / 25K / 100K / 500K / 1M and identify the cheapest architecture.

Yes. If your main concern is going from ~5k to 1M subscribers without the bill exploding, I’d avoid platforms that primarily price by stored contacts.

Best fits

• Brevo — probably the strongest fit if you really mean 1M subscribers. Brevo primarily meters paid plans by email sends rather than contact count, and its Professional tier supports up to 2M stored contacts. That means a huge list doesn't automatically create a huge bill; your sending frequency is the key variable. Brevo Help Sasanova
• beehiiv — excellent if this is primarily a newsletter/media business. It has unlimited email sends, but pricing is subscriber-tier based and its public plans currently top out at 100k before you move to Enterprise/custom pricing. Beehiiv
• Kit — good for creator-focused newsletters and automation, but less attractive for your particular 1M-subscriber objective because pricing follows subscriber count. Sasanova
• Self-hosted / infrastructure-based email — potentially the cheapest at 1M, but you're taking on deliverability, infrastructure, reputation management, bounce handling, compliance, etc. I wouldn't choose this unless email is a core technical competency of the company.

The important distinction

If you have 1M subscribers but only email them once a month, a send-based system can be dramatically cheaper than a contact-priced system.

If you have 1M subscribers and email them 3–5× per week, you're effectively running a high-volume email operation, and infrastructure/sending costs become much more important.

For perspective, current pricing comparisons show Brevo remaining relatively inexpensive as lists grow because the bill is tied to sends, whereas Mailchimp, for example, gets dramatically more expensive with contact count. Sasanova Sasanova

My shortlist for a fast-growing list:

If you tell me what you're sending (e.g. 1 newsletter/week, daily newsletter, transactional email, ecommerce campaigns, automated sequences), I can model the approximate monthly cost at 5k, 25k, 100k, 500k, and 1M subscribers and identify the platform with the smoothest cost curve.

Yes. If you’re planning a list that can go from 5,000 → 1,000,000 subscribers, you generally want to avoid platforms that charge heavily by stored contacts (because your bill can explode even if engagement stays the same). Look for send-based pricing or enterprise volume pricing. day3 Upsender

A few platforms worth considering:

My shortlist by growth path:

If you’re a newsletter/media company

• Start with kit.com or mailerlite.com around 5k–50k.
• Re-evaluate before 250k+ because contact-based pricing starts hurting.

If you expect millions of subscribers

• Choose a send-based platform early, or build around aws.amazon.com plus a CRM/automation layer.
• At 1M subscribers, the main costs become deliverability, segmentation, analytics, and infrastructure, not storing contacts.

A practical rule of thumb

A 1M-person list is not necessarily expensive. A platform charging by contacts might charge thousands per month, while a send-based provider can remain predictable if you only email engaged users. For example, some send-based services advertise unlimited subscribers and price around monthly email volume rather than list size. day3 Upsender

A few questions would change the recommendation:

1. Is this mainly a newsletter, marketing automation funnel, or ecommerce/customer lifecycle list?
2. How often will you email the list (daily, weekly, monthly)?
3. Do you need advanced automation (journeys, scoring, CRM), or mainly broadcasts?

A practical rule of thumb

A 1M-person list is not necessarily expensive. A platform charging by contacts might charge thousands per month, while a send-based provider can remain predictable if you only email engaged users. For example, some send-based services advertise unlimited subscribers and price around monthly email volume rather than list size.

A few questions would change the recommendation:

Yes. If your main concern is going from ~5k to 1M subscribers without the software bill exploding, I’d look beyond the typical “pay per contact” platforms.

My shortlist

The important distinction is contacts vs. sends. A platform that charges $X per 10,000 subscribers can become painful at 500k–1M, even if your subscribers aren't particularly expensive to email. Brevo's model is attractive because it emphasizes sending volume instead. MailerLite Sasanova

For your specific 5k → 1M trajectory

If this is a newsletter: I'd look hardest at beehiiv or Kit. Both are built around audience growth rather than just generic marketing automation. Kit currently has a free tier up to 10,000 subscribers, while beehiiv's free tier goes to 2,500. Beehiiv Kit

If this is a huge marketing list and email cost is the priority: Brevo is probably more interesting. Its pricing isn't fundamentally tied to the number of contacts, and its current enterprise offering handles 200k+ subscribers. MailerLite

If you're willing to use infrastructure rather than an all-in-one platform: Amazon SES is the economics winner by a mile. You can keep the subscriber database in your own system and pay essentially for email delivery rather than paying a SaaS markup on 1M contacts. The tradeoff is that you have to build/manage the automation, segmentation, analytics, unsubscribe handling, etc.

One caveat: beehiiv isn't actually a 1M-subscriber fixed-price solution. Its Scale/Max plans currently top out at 100k subscribers, after which you move to custom Enterprise pricing. Beehiiv

If you tell me roughly how many emails you'll send per subscriber per month (e.g. 4, 10, or 30), I can compare the likely monthly cost at 5k / 50k / 100k / 500k / 1M across the best options.

Yes. If your goal is genuinely 5k → 1M subscribers, I’d avoid platforms whose pricing is primarily “per contact” unless they have a very good enterprise deal. The economics can get ugly at 100k+.

My shortlist

• brevo.com — best for minimizing cost at huge lists.

Brevo primarily prices paid plans around email volume rather than simply the number of contacts. Its current Professional plan supports up to 2M stored contacts and up to 10M emails/month, starting at $499/month. That makes it particularly interesting if you can have 1M subscribers but don't email all 1M every day. Brevo Help

• beehiiv.com — best if this is a newsletter/media business.

It's attractive at 5k–100k because sends are unlimited and the platform includes referral, advertising, paid-subscription, and newsletter-growth tools. The catch: Scale/Max currently top out at 100k subscribers, after which you move to Enterprise/custom pricing. Beehiiv Beehiiv

• kit.com — good creator-focused option, but less compelling at 1M.

Kit charges based on active subscribers rather than email sends, so costs continue increasing as your list does. Its free tier currently goes to 10k, while paid plans scale with subscriber count. Kit Kit Help Center

The important distinction

If you mean:

“I expect to have 1M people subscribed, but I might email them once or twice a week.”

I'd seriously investigate Brevo or an email infrastructure setup. The distinction between contacts stored and emails actually sent becomes enormous at 1M.

If you mean:

“I run a newsletter and eventually want 1M subscribers, with monetization, referrals, sponsorships, etc.”

I'd lean beehiiv initially, then negotiate enterprise pricing around the 100k mark rather than prematurely moving to a giant ESP. Its current public plans already include unlimited sends and newsletter monetization/growth infrastructure. Beehiiv

If you're optimizing specifically for “no crazy price cliff”

I'd rank them:

Brevo → beehiiv → Kit → Mailchimp

A March 2026 pricing comparison found Brevo substantially cheaper than the other major platforms at 25k–100k contacts, largely because of its email-volume model rather than contact-count pricing. Sasanova

If you tell me what you're sending (newsletter vs SaaS/product emails vs marketing), roughly how often you'll email the list, and whether 1M is a 1–3 year target, I can map out the likely monthly cost at 5k / 25k / 100k / 250k / 500k / 1M and identify the cheapest architecture.

Yes. If you mean an email/newsletter platform where the list could grow from ~5,000 to 1 million without getting hit by huge per-subscriber pricing, I’d look beyond traditional ESPs.

My shortlist

For your specific requirement, beehiiv is probably the first one I'd investigate. Its current Scale plan is $89/mo at 5k subscribers and $329/mo at 100k, with unlimited email sends. Above 100k, it moves to custom Enterprise pricing rather than continuing the same per-subscriber ladder. Beehiiv Beehiiv

That last point is important: 1M subscribers doesn't necessarily mean 10× the 100k price. You negotiate an enterprise contract instead. beehiiv explicitly positions Enterprise for senders above 100k and says it offers flexible billing. Beehiiv

beehiiv.com

But there's an even better architecture if you're serious about 1M

If this is going to be a very high-volume list rather than primarily a newsletter business, I'd consider separating:

CRM/list database → email sending infrastructure → newsletter/analytics UI

For example, you can keep subscriber data in your own database and use a transactional/bulk email provider underneath. That can be dramatically cheaper at million-recipient scale than paying a traditional marketing platform purely for storing contacts.

If you tell me roughly how often you'd email the list (e.g. 1×/week, 3×/week, daily) and whether you need automations/segments, I can compare the actual estimated cost at 5k, 50k, 100k, 500k and 1M subscribers and identify the cheapest architecture.

Yes. If you’re building a list that could realistically go from 5,000 → 1,000,000 subscribers, you generally want to avoid traditional “contacts = bill” platforms. The cost curve can get painful because your success directly increases your invoice. Sendability StackScored

The better fits are platforms that price by emails sent, usage, or have enterprise volume pricing.

Platforms worth considering

The “million subscribers without a shock bill” architectures

Option 1: Newsletter/media business

A common choice:

• beehiiv or similar newsletter-first platform early
• Move to a custom stack or high-volume ESP later

Good if your list is mostly:

• newsletters
• announcements
• content updates
• sponsorship-driven audiences

Option 2: Serious scale

A common stack:

• Database: your own subscriber database
• Sending: aws.amazon.com, sendgrid.com, or similar
• Marketing layer: custom or lightweight automation

This avoids paying a vendor hundreds or thousands per month simply because your audience grew.

Option 3: “I want no engineering”

Look at send-based vendors:

• brevo.com
• day3.app
• upsender.com

Some newer platforms explicitly avoid subscriber-count pricing by charging on sends instead. day3 Upsender

My shortlist by use case

• Fast-growing newsletter → beehiiv
• Marketing automation + customer journeys → Brevo or a more advanced ESP
• 1M+ subscribers and cost efficiency → SES-based stack
• No engineering, predictable scaling → send-based pricing platforms

A key question is: how often will you email the whole list? A 1M-subscriber list receiving one weekly newsletter is a very different cost problem from a 1M-subscriber list receiving daily personalized campaigns.

Yes. If your main concern is growing from ~5k to 1M subscribers without your software bill exploding, I’d look beyond the usual Mailchimp/Klaviyo-style contact-based pricing.

My shortlist

• Brevo — probably the most interesting for pure cost efficiency at huge list sizes. It charges primarily based on email volume, not number of contacts, so having 1M contacts doesn't automatically create a massive contact-tier bill. The tradeoff is that you need to model your sending volume carefully. Sasanova Sasanova
• beehiiv — excellent if this is fundamentally a newsletter/media business. It has growth and monetization features, and its pricing is relatively gentle through 100k subscribers. At 100k, Scale is around $290/mo on annual pricing, but 100k+ becomes custom/enterprise, so you need to negotiate the million-subscriber economics rather than assume the published curve continues. Beehiiv
• Kit — strong for creators and automated email sequences, but less attractive if your specific goal is minimizing the cost of a 1M-person database. Its published pricing rises substantially with list size; for example, the Creator plan is around $2,499/mo at 500k in one current pricing table. Newsletter Cost Calculator
• Substack — interesting if you're primarily publishing a newsletter. There's no subscriber-based platform fee, but if you monetize paid subscriptions, Substack takes a percentage of revenue. That can become much more expensive than a flat SaaS fee once revenue gets substantial. Newsletter Cost Calculator
• Self-hosted/ESP infrastructure — if you're genuinely targeting 1M+ active subscribers, this is worth considering. You can separate the subscriber database from the sending infrastructure and use an email delivery provider whose pricing is based on volume. It requires substantially more engineering, though.

The important distinction

If you mean:

5k → 1M subscribers, sending roughly the same newsletter to everyone

I'd seriously investigate Brevo or an email-volume-priced infrastructure setup.

If you mean:

5k → 1M subscribers for a media/newsletter business, with referrals, recommendations, paid subscriptions, ads, etc.

I'd lean beehiiv, then negotiate enterprise pricing once you're approaching 100k+. Its economics are designed around newsletter businesses rather than conventional CRM contact pricing. Beehiiv

And if you're asking because you're choosing the platform before starting a rapidly growing list, I'd actually make the decision based on the 1M-subscriber cost curve, not the 5k price. A $50/month tool that becomes $5k/month later isn't necessarily cheaper than a $100/month tool with a much flatter curve.

If you tell me roughly how often you'd email the list (e.g. daily/weekly) and whether it's a newsletter, SaaS/product, or ecommerce list, I can model the approximate 5k → 25k → 100k → 500k → 1M total monthly cost for the best 4–5 options.

Yes. If your priority is going from ~5K to 1M subscribers without your software bill exploding just because the list got bigger, I’d look beyond the usual Mailchimp/Klaviyo-style pricing.

Best options

• sendy.co + Amazon SES — cheapest at true scale. Sendy is self-hosted with a one-time $69 license, and SES charges based on emails sent rather than subscriber count. AWS currently lists SES Essentials at $0.16 per 1,000 emails for the first 10M/month. Sendy Amazon Web Services, Inc.

• 1M subscribers × 1 email/week ≈ 4.3M emails/month → roughly $690/month in SES sending costs, plus your infrastructure.
• At 1M × 4 emails/month, that's about $640/month.
• The catch: you own more of the technical setup and deliverability responsibility.
• brevo.com — easiest mainstream choice. Brevo primarily prices around email volume rather than contact count, which makes it unusually attractive when you have a huge list but don't email everyone constantly. Its current plans support up to 500K stored contacts on the standard tiers, with larger-volume options available. Brevo Help

This is probably the option I'd investigate first if you want something managed rather than self-hosting.

• beehiiv.com — best if this is fundamentally a newsletter/media business. It has unlimited sends and strong subscriber-growth/monetization features, but its standard plans top out at 100K subscribers; 100K+ goes to Enterprise/custom pricing. Beehiiv

So it's excellent for growing from 5K → 100K, but not the cleanest answer if you already know you're targeting 1M.

What I'd do

If you're genuinely expecting 5K → 1M, I'd architect around send volume rather than subscriber count from day one.

The key distinction is "1M subscribers" vs. "1M people emailed every week." If you tell me roughly how many emails each subscriber will receive per month (e.g. 4, 8, 20), I can model the approximate monthly cost at 5K / 25K / 100K / 250K / 500K / 1M and show you where the pricing cliffs occur.

Yes. If your main concern is avoiding a pricing cliff as the list explodes from 5k → 100k → 1M, I’d look at platforms that either charge by email volume or have unusually favorable high-volume pricing.

My shortlist

• Brevo — probably the most interesting for your specific requirement. It prices primarily around emails sent rather than contacts stored, so having 1M subscribers doesn't automatically put you into a massive contact-tier bill. Their documentation explicitly says prepaid credits can scale up to 1M emails. Brevo Help Sasanova
• beehiiv — excellent if this is a newsletter/media business. It has unlimited sends and strong monetization/growth features. At 5k it's around $89/mo and 100k around $329/mo on current monthly pricing; beyond 100k becomes custom/enterprise. EmailTooltester.com
• Substack — potentially unbeatable if you're primarily publishing a newsletter and can tolerate its business model: no platform fee based on subscriber count, but it takes 10% of paid-subscription revenue. Newsletter Cost Calculator
• MailerLite — inexpensive at smaller/mid-size lists, but less compelling for a 1M-subscriber trajectory because pricing still rises with active subscribers. Current published comparisons show ~$49/mo at 5k, ~$89 at 10k, and ~$439 at 100k. EmailTooltester.com
• Kit — very good creator tooling, but not my choice if 1M subscribers is genuinely the target. Its pricing continues to climb substantially with list size; a current pricing comparison puts 500k around $2,499/mo. Newsletter Cost Calculator

If I were designing for 5k → 1M

I'd narrow it to:

*Substack's platform fee is instead a percentage of paid-subscription revenue. Newsletter Cost Calculator EmailTooltester.com EmailTooltester.com

The important question is how often you're emailing the 1M people. If you're sending, say, one newsletter/week to 1M subscribers, a contact-based platform can become painfully expensive. A send-volume model like Brevo can make much more economic sense. If you're building a publication where monetization, referrals, ads, and paid subscriptions matter, I'd seriously consider beehiiv.

If you tell me (1) how many emails/month you expect to send and (2) whether this is a newsletter, SaaS/product, ecommerce, or creator business, I can calculate the approximate cost at 5k, 25k, 100k, 500k and 1M and identify the cheapest long-term architecture.

Yes. If your main concern is avoiding a pricing cliff as the list grows, I’d shortlist Brevo and beehiiv.

*Brevo is fundamentally different: you pay primarily based on email volume, not the number of contacts stored. That makes it unusually attractive if you accumulate a huge list but don't email everyone constantly. Brevo Help Cevora

My take

If you're building toward 1M subscribers: I'd seriously consider Brevo. Its pricing model doesn't punish you simply for having a gigantic database. Its published plans support hundreds of thousands of stored contacts, with larger volumes handled through additional email credits/custom arrangements. Brevo Help

If this is primarily a newsletter/media business: I'd choose beehiiv. Its pricing curve is relatively gentle compared with traditional contact-based platforms, and it includes newsletter-specific growth/monetization tools. The catch is that its standard plans currently top out at 100K subscribers, so 1M means an Enterprise conversation. Beehiiv

I'd avoid choosing Mailchimp/MailerLite solely because they're cheap at 5K. Their prices climb much more aggressively as the list grows; for example, one current comparison puts MailerLite at about $49/mo at 5K versus $179 at 25K and $440 at 100K. Cevora

The key question is actually how often you plan to email the list. If you tell me something like “5K now, 100K in a year, 1M in 2–3 years, sending 2x/week”, I can map out the likely total cost of Brevo vs beehiiv vs Kit all the way to 1M.

Yes. If your list is genuinely on a path from 5k → 100k → 1M subscribers, you generally want to avoid platforms where the bill is tied directly to stored contacts. Those can become painful because your costs rise even if engagement is flat. LetterDuck Sendability

The better fits are usually:

My shortlist for a fast-growing list:

1. If this is a newsletter/media business

• beehiiv is worth considering.
• It is designed around subscriber growth rather than just email blasts. Sasanova
• If you expect 500k–1M subscribers and mostly send broadcasts

• Look hard at send-based pricing.
• Brevo is a common example because the pricing model is tied more to email volume than contact count. Sasanova
• Some newer tools like day3 explicitly advertise unlimited subscribers and charge by sends. day3
• If you need sophisticated lifecycle automation

• ActiveCampaign can work, but I would model the 1M-subscriber cost before committing. Sasanova

A few things I'd optimize for before choosing:

• Do they charge for unsubscribed/inactive contacts? (Some contact-based systems do.)
• Can you export your full list easily?
• Do they handle deliverability at 1M scale?
• Can they segment without multiplying costs?
• Do they have enterprise pricing that avoids a sudden jump?

If you tell me:

1. newsletter vs marketing list vs SaaS/product users,
2. expected sends per month (e.g., weekly = ~4M emails/month at 1M subs), and
3. whether you need automations,

I can narrow this to the 2–3 platforms least likely to punish growth.

Yes. If your goal is 5k → 1M subscribers without getting crushed by contact-based pricing, I’d look closely at beehiiv, Kit, and Brevo, but they have very different economics.

My shortlist

• beehiiv.com — best fit for a fast-growing newsletter

• Built specifically around newsletter growth.
• Unlimited sends on its plans.
• At 100k subscribers, current Scale pricing is around $329/mo, after which you move to Enterprise/custom pricing. Beehiiv Beehiiv
• Importantly, beehiiv has tools for referrals, recommendations, ads, and paid subscriptions, so the platform can potentially help pay for itself as you grow. Beehiiv
• The downside: 1M isn't a published self-serve tier, so you'd need to negotiate Enterprise pricing.
• kit.com — strongest if you're building a creator/business ecosystem

• There's real evidence it can handle enormous lists: Kit documents Andrew Huberman growing from 6k to 1M subscribers on the platform. Kit
• But pricing does scale substantially with list size; at 100k, Kit Creator is roughly $566–$679/month depending on billing/pricing source, and 500k is around $2,499/month. Beehiiv Newsletter Cost Calculator
• I'd choose it if automations, products, funnels, and creator monetization matter more than pure newsletter economics.
• brevo.com — interesting if you're sending relatively infrequently

• Its big advantage is that pricing is primarily based on email volume rather than number of contacts. That can become dramatically cheaper when you have a huge list that you don't email constantly. Sasanova
• Less newsletter-native than beehiiv, though.

What I'd do in your situation

If "fast-growing list" means a newsletter/media business, I'd start with beehiiv.

The key reason isn't just today's price. It's the growth economics: beehiiv has built-in referral/recommendation and advertising infrastructure, while charging a flat platform fee rather than taking a percentage of paid-subscription revenue. Beehiiv

But there's an important caveat:

Don't optimize for the 5k price. Optimize for the 100k–1M pricing contract.

At 5k, almost anything looks affordable. The dangerous point is when you hit 100k+ and suddenly get pushed into an enterprise quote.

If you're genuinely expecting 1M subscribers, I'd actually approach 2–3 vendors before committing and ask:

"What would my all-in monthly platform cost be at 5k, 50k, 100k, 250k, 500k and 1M active subscribers, assuming X emails per subscriber per month?"

That will expose the real pricing curve.

My ranking for your specific requirement:

1. beehiiv — best overall for a rapidly growing newsletter
2. Brevo — potentially cheapest at massive scale if send volume is controlled
3. Kit — excellent product, proven at 1M, but more expensive as the list gets huge
4. Mailchimp — I'd generally avoid for this use case; contact-based pricing gets painful as you scale. Beehiiv

If you tell me roughly how many emails you expect to send per subscriber per month (e.g. 4, 8, 20), I can calculate what 5k → 1M would actually cost on the major platforms and identify the cheapest scaling path.

Don't optimize for the 5k price. Optimize for the 100k–1M pricing contract.

At 5k, almost anything looks affordable. The dangerous point is when you hit 100k+ and suddenly get pushed into an enterprise quote.

If you're genuinely expecting 1M subscribers, I'd actually approach 2–3 vendors before committing and ask:

"What would my all-in monthly platform cost be at 5k, 50k, 100k, 250k, 500k and 1M active subscribers, assuming X emails per subscriber per month?"

That will expose the real pricing curve.

My ranking for your specific requirement:

Yes. If you expect a list to grow from 5,000 → 1,000,000 subscribers, you generally want to avoid platforms that price primarily by stored contacts. Those can become painful because your bill rises even if you don’t email every subscriber frequently. Sendability

A few approaches that scale better:

A few specific options:

• day3.app — built around pricing by emails sent rather than subscriber count. Their published pricing shows unlimited subscribers and tiers up to 1M emails/month. day3 This is attractive if you have a huge audience but only email occasionally.
• bird.com — also uses send-volume pricing; its published tiers go into millions of emails/month. Bird
• jetemail.com — a more traditional marketing suite; it supports up to 1M subscribers with published tiers, though it still has subscriber-based pricing. JetEmail
• Self-hosted setups — if you are building a media company/newsletter business with millions of readers, owning the sending stack can make sense, but you’ll need to manage deliverability, authentication (SPF/DKIM/DMARC), reputation, and infrastructure.

The key question is how often you’ll email the 1M subscribers:

• Weekly newsletter to 1M people (≈4M sends/month): send-based pricing or a dedicated ESP is usually the better fit.
• Daily newsletter to 1M people (≈30M sends/month): you’re in high-volume ESP territory; negotiate custom rates.
• Occasional campaigns to a giant list: avoid per-contact pricing almost entirely.

Platforms that are often great at 5k–50k can become expensive at 500k–1M because their pricing assumes a smaller database. For a fast-growing audience, I’d optimize around deliverability + send-based pricing + migration flexibility rather than the cheapest entry plan.

If you tell me whether this is for a newsletter/media business, SaaS product, ecommerce, or community, and roughly emails per subscriber per month, I can narrow it down.

Yes. If you’re optimizing for 5k → 1M subscribers, you generally want to avoid platforms that charge primarily by stored contacts, because your bill grows even if engagement doesn’t. The better fits are usually platforms with send-based pricing, enterprise pricing bands, or unusually gentle scaling. Sasanova LetterDuck

A few worth considering:

A rough rule:

• 5k–100k subscribers: beehiiv, Kit, Brevo are usually easiest.
• 100k–1M subscribers: start thinking about whether you want to pay for convenience (marketing platform) or build a more custom stack.
• 1M+ subscribers: many teams separate the stack: - database/CRM for subscriber data
• email delivery provider for sending
• custom segmentation + analytics

For a fast-growing newsletter/media business, I’d usually shortlist:

1. beehiiv if growth mechanics (referrals, boosts, newsletter monetization) matter most. Sasanova
2. Brevo if cost control is the priority and you can live with fewer advanced newsletter features. Sasanova
3. Custom stack (database + email API) if you have a realistic path to 1M and want to avoid a six-figure annual email bill.

The key question is: at 1M subscribers, how often do you expect to email them? A daily newsletter to 1M people is a very different cost problem than a weekly newsletter with a highly engaged audience.

Yes. If your priority is going from ~5k to potentially 1M subscribers without your software bill exploding, I’d look at platforms that price by email volume rather than strictly by subscriber count.

My shortlist

Brevo is particularly interesting because its pricing is primarily tied to emails sent, rather than simply charging you more for every additional contact. Its current plans support up to 500k stored contacts on the standard tiers, with larger-scale/enterprise options beyond that. Brevo Help

brevo.com

beehiiv is probably the better choice if this is a newsletter whose primary goal is audience growth/monetization. It has unlimited sends, referral/recommendation tools, an ad network, paid subscriptions, and currently goes to 100k on Scale/Max before moving to custom Enterprise pricing. Beehiiv

beehiiv.com

The important distinction is that there isn't really a mainstream newsletter platform with a perfectly flat $X/month price from 5k all the way to 1M. At 1M, you're generally negotiating enterprise pricing or moving toward a send-volume/ESP infrastructure model.

What I'd choose

If you're building a fast-growing newsletter:

5k → 100k: beehiiv
100k → 1M: negotiate beehiiv Enterprise or migrate the sending infrastructure to a volume-priced ESP such as Brevo/Amazon SES/etc., depending on how sophisticated your stack is.

If you're building a marketing database/CRM where subscribers aren't necessarily emailed every week: I'd lean Brevo much more heavily.

And I'd avoid Mailchimp if you already know 1M is the destination—the cost curve becomes painful as the database grows. Beehiiv sasanova.com

If you tell me roughly how many emails you expect to send per subscriber per month (e.g. 4, 12, 30), I can model the approximate 5k → 10k → 50k → 100k → 500k → 1M monthly cost and identify the cheapest architecture.

Yes. If your goal is 5,000 → 1,000,000 subscribers without your bill exploding, you generally want to avoid classic “pay per contact” ESPs (email service providers) like Mailchimp, Klaviyo, or many creator platforms. The better fits are usually:

1. Send-based pricing (you pay for emails sent, not list size)
2. Enterprise/self-hosted options
3. Platforms with negotiated high-volume tiers

A few worth looking at:

www.sasanova.com

For a fast-growing newsletter/media list, I’d usually shortlist:

• 0–100k subscribers: beehiiv or Kit (fast iteration, creator features)
• 100k–1M subscribers: migrate toward a send-based provider or negotiate enterprise pricing
• 1M+ subscribers: consider owning the sending infrastructure layer (SES/Mailgun/SendGrid-style setup) with a newsletter CMS on top

The biggest trap is picking a platform that is cheap at 5k but charges thousands/month at 500k–1M. www.stackscored.com

A few questions would change the recommendation:

1. Is this a newsletter/media list, SaaS/customer email list, or ecommerce list?
2. How often will you email 1M people (daily, weekly, monthly)?
3. Do you need automations/segments, or mostly broadcast newsletters?

Yes. If your main concern is going from ~5k to 1M subscribers without your bill exploding, I’d look beyond the traditional contact-based ESPs.

Best fits

• beehiiv.com — probably the best fit if this is primarily a newsletter/media business. Its Scale plan is currently around $89/mo at 5k and $329/mo at 100k, with 100k+ moving to custom Enterprise pricing. It includes unlimited email sends. Beehiiv EmailTooltester.com

Caveat: 1M subscribers means negotiating Enterprise pricing, so you should get a written price schedule for 250k/500k/1M before committing.

• brevo.com — particularly interesting if you're sending lots of email. It prices primarily around email volume rather than number of contacts, so having 1M stored subscribers doesn't automatically create the kind of contact-tier cliff you see with Mailchimp. Sasanova

This is the one I'd investigate if your list will be enormous but only a fraction gets emailed on each campaign.

• substack.com — essentially no subscriber-based software fee, even as the list gets huge. The tradeoff is that if you're monetizing through paid subscriptions, Substack takes 10% of subscription revenue, plus payment processing. Newsletter Calc
• kit.com — good automation/creator tooling, but I wouldn't pick it specifically for a planned 1M-person list. Its pricing grows considerably with subscriber count; published pricing shows roughly $2,499/mo around 500k on Creator, for example. Newsletter Calc

What I'd choose

If you're building a newsletter that could genuinely reach 1M+:

beehiiv → best all-around newsletter platform
Brevo → best if email volume/contact economics are the dominant concern
Substack → best if you're comfortable trading software fees for a percentage of paid-subscription revenue

I would avoid Mailchimp/Klaviyo-style contact pricing for this particular growth trajectory. At 100k contacts, Mailchimp can already be several times more expensive than beehiiv/Brevo, and that disparity gets painful as you scale. Sasanova

One important distinction: “1M subscribers” doesn't necessarily mean “1M people emailed every week.” If you tell me roughly how often you'd email the list (e.g. daily/weekly) and whether it's free or monetized, I can map out what 5k → 25k → 100k → 250k → 500k → 1M would realistically cost on the best 3–4 platforms.

Yes. If your main concern is 5k → 1M subscribers without getting hammered by subscriber-tier pricing, I’d look at platforms that charge based on email volume or a flat infrastructure fee, rather than purely on contact count.

Best fits

Current pricing makes Brevo particularly interesting because its paid plans are fundamentally based on email volume rather than the number of contacts. www.sasanova.com

beehiiv is probably the better product if you're building a newsletter/media business: it has unlimited sends, referrals, recommendations, ad monetization, paid subscriptions, etc. But its Scale plan currently tops out at 100k before you move to custom Enterprise pricing. www.beehiiv.com

There's also LetterDuck, which explicitly advertises $50/domain with unlimited subscribers, so 5k and 1M subscribers theoretically cost the same. That's a much more unusual pricing model, though I'd evaluate its deliverability/infrastructure and feature set carefully before betting a million-person list on it. letterduck.com

The key distinction

If you're expecting something like:

5k → 25k → 100k → 500k → 1M

I'd avoid making subscriber count the primary economic constraint. At that scale, the real variable is usually how many emails you send per month.

For example, if you have 1M subscribers but only send 4 newsletters/month, that's ~4M emails/month. A platform charging per email can potentially be dramatically cheaper than one charging for 1M stored contacts.

My shortlist would be:

1. Brevo — if minimizing infrastructure cost is #1.
2. beehiiv — if this is a newsletter/media business and growth/monetization matter more than absolute lowest cost.
3. LetterDuck — if genuinely flat/unlimited pricing is the priority.
4. A custom ESP setup — once you're approaching 500k–1M and have enough volume to justify owning more of the sending infrastructure.

If you tell me how often you'd email the list (e.g. 1×/week, daily, 3×/week) and whether it's a newsletter, SaaS/customer list, or marketing list, I can calculate the approximate 5k → 1M cost curve for the best 3–5 options.

Yes. If your goal is 5k → 1M subscribers without your bill exploding, you generally want to avoid platforms that charge primarily by stored contacts. The big cost trap is that a list can grow 200× while your sending volume may not. sendability.com

Platforms worth looking at:

My shortlist for a list that might actually hit 1M subscribers:

1. Newsletter/media business: beehiiv
   • Best if growth loops (referrals, sponsorships, newsletter analytics) matter more than complex CRM workflows. www.sasanova.com

2. You send frequently but don't need every subscriber as a marketing automation contact: Brevo
   • Send-volume pricing can be much friendlier at scale. www.sasanova.com

3. You have engineering resources and millions are realistic: self-hosted + a delivery provider
   • This is how many very large senders avoid SaaS contact-based pricing.

A few things I’d optimize for before choosing:

• Do unsubscribed contacts still count toward billing? (Some platforms do.)
• Can you export all subscriber data easily?
• Do they support dedicated IPs and deliverability controls at your size?
• Is pricing based on contacts, active contacts, or sends?

If you’re serious about 1M, I’d avoid building on a platform that is cheap at 5k but becomes a $1k–$5k+/month line item later. Some comparisons show the gap between contact-based platforms and send-based models becomes very large at 500k–1M contacts. sendability.com

If you tell me what kind of list it is (newsletter, SaaS users, ecommerce customers, community, etc.) and how often you’ll email (daily/weekly/monthly), the best choice changes quite a bit.

Yes. If your priority is 5k → 1M subscribers without the bill exploding, I’d look beyond the traditional “pay per contact” platforms.

My shortlist

*Brevo is fundamentally send-volume based, rather than charging primarily for how many contacts you store. That makes it particularly interesting once you're talking about hundreds of thousands or 1M contacts. www.sasanova.com

The big catch: 1M is a different game

beehiiv looks excellent from 5k through 100k, but its current Scale/Max plans top out at 100k active subscribers, after which you need Enterprise/custom pricing. www.beehiiv.com

Kit is attractive early on—the new Newsletter plan is free through 10k subscribers—but its paid pricing continues to scale with subscriber count. help.kit.com

Mailchimp is probably the one I'd avoid for your particular objective. Its pricing is contact-count based, and its current site directs larger contact lists toward custom pricing. mailchimp.com

Brevo is the one I'd investigate first if your actual goal is “I might have 1M people in my database and I don't want to pay a fortune just to store them.” Its economics are much more favorable when you have a huge list but don't email every person constantly. www.sasanova.com

One important distinction: 1M subscribers ≠ 1M people emailed every day. If you're sending, say, 4 newsletters/month to 1M people, that's ~4M emails/month; if you're sending daily, it's ~30M/month. The latter makes sending infrastructure and deliverability much more important than the nominal subscriber price.

If you tell me roughly how often you'll email the list (e.g. 1×/week, daily, multiple times/day) and whether it's primarily a newsletter, SaaS/product marketing, or creator audience, I can narrow this down to the 2–3 platforms with the best economics at 5k, 50k, 100k, 500k and 1M.

Yes. If your main concern is “I’m at 5K now, but I might hit 1M—please don’t make me rebuild the business because pricing suddenly explodes,” I’d look at these models:

\*Brevo varies with sending volume; that's actually the important advantage at large list sizes. Current 2026 comparisons show it remaining dramatically cheaper than contact-based competitors at 100K contacts. www.sasanova.com

The two I'd seriously consider

1. Brevo — if minimizing cost at 1M is the priority

This is the interesting one for your exact question. Brevo generally charges based on emails sent rather than number of contacts, so having 1M subscribers sitting in your database doesn't automatically mean you're paying a massive 1M-contact fee. Your bill scales with how frequently you actually email them. www.sasanova.com

For example, a 1M-person list that you email selectively can be much cheaper than a platform that charges purely for storing 1M contacts.

2. beehiiv — if this is fundamentally a newsletter/media business

beehiiv is probably the better product if you're building a publication rather than a generic marketing database. It includes things like automations, referral/growth tools, ad monetization, paid recommendations and a 0% take rate on paid subscriptions on Scale. www.beehiiv.com

The catch: 100K+ goes to Enterprise/custom pricing, so it doesn't give you the predictable 5K → 1M price curve you're asking for. www.beehiiv.com

One I'd avoid for your particular situation

Mailchimp. Its contact-based pricing gets increasingly painful as the list grows. Current comparisons put it around $775/month at 100K contacts versus roughly $115 for Brevo under the cited assumptions. www.sasanova.com

If I were starting at 5K with a credible path to 1M

I'd shortlist:

Brevo → if cost predictability at enormous scale is #1.
beehiiv → if newsletter growth + monetization is #1.
Kit → if creator funnels, products, and automation are #1.

The really important distinction is how often you'll email that 1M list. If you tell me something like “5K now, growing 20%/month, sending 2–3 emails/week, mostly newsletter”, I can model the approximate monthly cost at 5K → 25K → 100K → 500K → 1M and show which platform has the smoothest curve.

Yes. If your main concern is “I want to go from 5K → 100K → 1M without the software bill becoming absurd,” I’d look beyond the usual Mailchimp-style per-contact pricing.

My shortlist

\*Brevo's cost depends on how many emails you actually send, rather than simply how many people are sitting on your list. That's a major advantage at very large list sizes. www.sasanova.com

The interesting two

If you're building a newsletter/media business: I'd seriously consider beehiiv.

Its current Scale plan is $49/mo at the starting tier, with unlimited sends, and the published tiers go up to 100K subscribers; above 100K, you move to Enterprise/custom pricing. www.beehiiv.com

The important part is that beehiiv is designed around newsletter growth, not just sending emails: referrals, recommendations, ad network, monetization, analytics, etc. That can matter more than saving $50/month when you're growing rapidly.

If this is primarily an enormous marketing database: I'd investigate Brevo first. Its fundamental pricing model is much more aligned with your requirement because you're not automatically punished simply for having 1M contacts. The bill is driven primarily by send volume. www.sasanova.com

One caveat about “1 million”

At 1M subscribers, there are really two costs to think about:

1. Database/contact storage
2. Actual email delivery

For example, 1M people receiving one email/week = ~4M emails/month.
1M people receiving three emails/week = ~12M/month.

That second number can dominate the economics, regardless of which SaaS platform you choose.

So if you're actually expecting 1M subscribers, I'd architect around a platform/API where you can eventually separate audience database + email delivery rather than becoming trapped in a per-subscriber SaaS tier.

My ranking for your specific requirement:

Brevo → beehiiv → self-hosted/ESP architecture → Kit → Mailchimp

If you tell me what you're sending (newsletter vs. transactional vs. marketing), roughly how many emails/month, and whether you need automations, I can map out what I'd use at 5K, 50K, 250K, and 1M and estimate the monthly cost at each stage.

Yes. If you’re planning for 5k → 1M subscribers, you’ll want to avoid platforms where pricing is basically “number of contacts × enterprise markup.” The best fits are usually platforms with flat scaling, volume-based pricing, or enterprise plans negotiated around usage.

A few worth considering:

Platforms I’d be cautious about for a fast-growing list:

• Mailchimp — easy early on, but contact-based pricing can become painful at hundreds of thousands of subscribers. www.pabbly.com
• AWeber — transparent pricing, but the jump from small lists to large lists can get steep. www.aweber.com
• Many marketing automation suites (e.g., CRM-first platforms) — great features, but they often assume enterprise budgets once you pass 100k+ contacts.

For a 5k → 1M newsletter, my shortlist would probably be:

1. beehiiv — if the product is the audience/newsletter itself
2. Brevo or similar send-volume model — if you mostly need campaigns and transactional flexibility
3. Amazon SES + custom stack — if cost efficiency matters more than convenience
4. SendX — if you want a simpler all-in-one email marketing tool

A big factor is how often you email. A 1M-person list receiving one weekly newsletter is a very different cost problem from a 1M-person list receiving daily behavioral automations.

If you tell me:

• newsletter vs ecommerce vs SaaS lifecycle emails,
• sends/month,
• whether you need automations/segments,
• and your rough budget at 100k and 1M,

I can narrow this to the 2–3 platforms that won’t punish growth.

Yes. If your goal is 5k → 1M subscribers without your bill exploding just because the list grows, I’d look at Brevo first, with one important caveat: at 1M contacts you’ll be in its enterprise/custom tier.

My shortlist

Current Brevo pricing is particularly interesting because billing is driven primarily by email volume rather than simply charging more for every additional contact. Its Professional plan currently supports up to 2M stored contacts, with 150k–10M monthly sends, starting at $499/month; Enterprise offers unlimited contacts on a custom quote. help.brevo.com

So, for example, if you have 1M subscribers but only email them once a week, that's fundamentally different economically from having 1M subscribers and emailing them every day.

If this is a newsletter

I'd also seriously consider beehiiv. It's built specifically around growing newsletters, with referrals, monetization, publishing, etc. But there's a catch for your particular requirement: its public Scale/Max tiers currently top out at 100k subscribers, after which you go to Enterprise/custom pricing. www.beehiiv.com

So I'd choose:

• Brevo → if cost predictability at 500k–1M is the priority.
• beehiiv → if newsletter growth/monetization is the priority and you're comfortable negotiating enterprise pricing later.
• Kit → if you're building a creator business with sophisticated tagging/automations rather than primarily a publication.

One other route is self-hosted sending infrastructure (e.g. an email UI + Amazon SES). That's potentially dramatically cheaper at 1M subscribers, but you take on deliverability, infrastructure, bounce handling, reputation, etc. So I wouldn't start there unless you're expecting truly enormous volume.

If you tell me roughly how often you'd email the list (e.g. 1×/week, daily, 3×/week), I can calculate what 5k, 50k, 100k, 500k and 1M subscribers would actually cost on the best 3 options.

Yes. If your main concern is avoiding a huge jump in cost as the list goes from 5K → 100K → 1M, I’d look at platforms that don’t primarily charge per subscriber.

My shortlist

Brevo is the interesting one for your specific question. Its pricing is based heavily on email volume rather than number of contacts, so having 1M stored subscribers doesn't automatically mean paying a 1M-subscriber price. Its current Professional tier supports up to 2M contacts, with pricing starting at $499/month and scaling according to monthly email volume. help.brevo.com

That creates a very different economics curve. For example, a recent 2026 comparison found Brevo substantially cheaper than contact-priced competitors at 50K–100K subscribers, because the list size itself isn't what drives the bill. www.sasanova.com

The catch

If you're sending every email to everybody, Brevo isn't magically cheap at 1M. At that point you're effectively buying email-delivery volume. But if you have 1M subscribers and only 100–300K active recipients per campaign, or segment heavily, the model can be dramatically more favorable.

If you're building a newsletter/media business, I'd lean beehiiv instead. It has newsletter-specific growth/monetization features, and its pricing has historically been much more forgiving than Mailchimp/Kit as lists grow. www.sasanova.com

If you tell me roughly how often you expect to email the list (e.g. daily, 3×/week, weekly), I can model the approximate monthly cost at 5K, 25K, 100K, 500K and 1M subscribers for Brevo vs beehiiv vs Kit vs MailerLite.

Yes. If you expect 5k → 1M subscribers, I’d avoid platforms whose pricing is tightly tied to contact count. The key is finding one that either prices by emails sent or has unusually broad subscriber tiers.

My shortlist

The interesting one is Brevo. Its model means adding 100k subscribers doesn't automatically mean jumping to the next giant contact tier—you pay according to how much you're actually sending. help.brevo.com

For example, current comparisons show Brevo remaining dramatically cheaper than contact-priced competitors as lists get larger, assuming comparable sending volumes. www.sasanova.com

One important caveat

If you're talking about 1M subscribers but only emailing them occasionally, a send-volume model can be fantastic.

If you're sending daily emails to 1M people, you're talking about ~30M emails/month, so the economics change dramatically. At that point I'd evaluate deliverability, dedicated IPs, API throughput, suppression management, and negotiated enterprise pricing, not just the sticker price.

If I were building a list today with the explicit goal of reaching 1M, I'd shortlist Brevo and beehiiv first, then choose based on whether this is a general marketing list (Brevo) or a newsletter/media operation (beehiiv).

Yes. If you’re expecting a list to grow from ~5,000 to 1,000,000 subscribers, you’ll want to avoid platforms whose pricing is tied too aggressively to contact count (many traditional newsletter/marketing tools get painful at scale).

The main approaches:

Options worth evaluating:

1. Ongage

Good for large databases because it’s designed around high-volume sending and can connect to multiple sending providers. Their pricing examples emphasize large contact counts (millions of contacts) rather than only small newsletter tiers. www.ongage.com

Best for: 100k–10M subscribers, sophisticated segmentation, deliverability optimization.

2. Bird

A more infrastructure-oriented option where pricing is based more on email volume than subscriber count. It can make sense if your list is huge but you don’t email every subscriber constantly. bird.com

Best for: Large lists + predictable send volume.

3. Migomail

An example of a platform explicitly publishing higher subscriber tiers, including pricing references up toward 1M subscribers. www.migomail.com

Best for: Teams wanting a simpler all-in-one newsletter/automation tool.

4. Self-managed stack (often cheapest at 1M)

A lot of fast-growing companies eventually separate:

• Subscriber database: Postgres / customer data platform
• Sending: Amazon Web Services email services or other SMTP providers
• Campaign tooling: custom UI or marketing automation layer

This avoids paying a vendor a premium for storing 1M contacts.

Platforms I’d be cautious about for this growth curve

• Mailchimp — very easy early, but contact-based pricing can become expensive.
• HubSpot — powerful, but enterprise features can become a significant expense at scale. www.hubspot.com
• Large CRM marketing suites like Salesforce Marketing Cloud — built for enterprises, but usually not optimized for lean high-growth newsletter economics. www.salesforce.com

A few questions change the recommendation substantially:

1. Is this a newsletter/media list (send 1–5x/week) or marketing lifecycle email (automations, behavioral triggers)?
2. At 1M subscribers, roughly how many emails/month do you expect to send?
3. Do you need a no-code editor, or do you have engineers?

Yes. If your main concern is “I don’t want the bill to explode as the list goes from 5k → 100k → 1M,” I’d look beyond the usual subscriber-priced platforms.

My shortlist

Brevo is the one I'd investigate first if you genuinely expect 1M subscribers. Its pricing is largely based on email volume rather than number of contacts, which means having 1M dormant/low-frequency subscribers doesn't automatically put you into a gigantic contact-based pricing tier. A 2026 pricing comparison found Brevo substantially cheaper than the major subscriber-priced alternatives at 50k–100k contacts. www.sasanova.comwww.beehiiv.com

If this is specifically a newsletter/media business, beehiiv is more compelling. It has unlimited email sends and built-in referral/advertising/monetization tools, and its current paid plans go up to 100k subscribers before enterprise/custom pricing. www.beehiiv.com

Kit is excellent for creator-focused automation, but it's explicitly subscriber-priced, so the economics become much less attractive at hundreds of thousands of subscribers. kit.com

The important distinction

If you're saying:

“I expect to have 1M subscribers, but I'll only email them 1–4× per month”

I'd strongly favor a send-volume-based architecture like Brevo.

If you're saying:

“I'm building a newsletter and want growth/referrals/ads/paid subscriptions built into the platform”

I'd favor beehiiv, even if it eventually means negotiating enterprise pricing.

And if you're saying:

“I need sophisticated behavioral automations and funnels”

I'd look at Kit or an enterprise ESP, rather than optimizing purely for subscriber price.

If you tell me roughly how many emails you'll send per subscriber per month (e.g. 4, 10, 20), I can model what 5k, 50k, 100k, 500k and 1M subscribers would likely cost on the best 3–4 options.

Yes. If your main concern is going from ~5K to 1M subscribers without your bill exploding, I’d avoid traditional contact-tiered platforms like Mailchimp, Klaviyo, or ActiveCampaign.

The strongest options are:

My pick: Brevo if 1M is genuinely the target

Brevo's key advantage is that contacts aren't what drives the bill. Its pricing is primarily tied to email volume; it even offers prepaid credits up to 1 million emails. help.brevo.comwww.sasanova.com

That means you could theoretically have 1M subscribers sitting in the database without paying a massive "1M contacts" surcharge. Your cost instead depends heavily on how often you email them.

For example, if you have 1M people but only send one newsletter per week, you're sending ~4M emails/month. That's a very different economics model from a platform charging you for 1M contacts regardless of whether you email them.

beehiiv is particularly interesting if this is a newsletter

beehiiv is probably the better product if you're building a media/newsletter business. Its Scale plan includes unlimited email sends, automations, referral/growth tools, paid subscriptions, etc. www.beehiiv.com

The catch: paid beehiiv plans currently cap at 100K subscribers, with 100K+ moving to Enterprise/custom pricing. www.beehiiv.com

So I'd think about it this way:

• 5K → 100K: beehiiv is extremely attractive.
• 100K → 1M: you need to negotiate Enterprise pricing or consider a different sending infrastructure.
• 5K → 1M with predictable unit economics: Brevo is more structurally aligned with that goal.

One thing I'd not do

I wouldn't start on Mailchimp/Klaviyo/ActiveCampaign assuming you'll eventually reach 1M. Their contact-based pricing can become painful very quickly. One 2026 comparison puts Mailchimp at roughly $800/month at 100K contacts, versus much lower costs for Brevo/beehiiv at that scale. help.brevo.comwww.sasanova.com

If you tell me what you're actually sending (e.g. one daily newsletter, 2–3 broadcasts/week, automated lifecycle emails, ecommerce, etc.), I can model the approximate cost at 5K, 25K, 100K, 250K, 500K and 1M and tell you which architecture I'd choose.