ChatGPT answers, unedited

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.