ChatGPT answers, unedited

If you're an agency running paid newsletters for multiple clients, I’d shortlist beehiiv and Ghost, with beehiiv usually the better operational fit.

🥇 My pick: beehiiv

beehiiv is unusually well suited to an agency model. One account can contain multiple independent publications, each with its own subscriber list, settings, domains and analytics. Its documentation explicitly describes using this setup for managing newsletters for multiple clients. www.beehiiv.com

The important distinction is ownership/billing:

• If your agency operates everything centrally, you can keep multiple client publications in one workspace.
• If each client needs their own login, billing, and ownership, beehiiv recommends giving the client a separate account and adding your agency as a team member. www.beehiiv.com
• Max supports up to 10 publications and unlimited team seats; Enterprise offers custom publication limits and more enterprise controls. www.beehiiv.comwww.beehiiv.com
• Paid subscriptions are supported, with beehiiv currently advertising 0% platform take on paid subscription revenue; Stripe processing fees still apply. www.beehiiv.comwww.beehiiv.com

That's a very good match for an agency where the desired structure is:

Client A → Publication A → Client A's Stripe/billing → Client A's subscribers
Client B → Publication B → Client B's Stripe/billing → Client B's subscribers

beehiiv also now has group subscriptions, which is useful if your agency sells subscriptions to companies or organizations rather than individual readers. www.beehiiv.com

beehiiv

🥈 Ghost — better if client ownership is paramount

Ghost is arguably the stronger architecture when each client should completely own their publication and customer/billing data.

Ghost's membership system supports free members, paid members, access tiers, and server-side gated content. docs.ghost.org Each publication can connect directly to its own Stripe account, and Ghost takes 0% of subscription revenue. ghost.org

It also supports multiple newsletters within a publication, with different audience segments receiving different newsletters. docs.ghost.org

The downside for an agency is that Ghost is less of a turnkey multi-client agency control plane. You'd generally create/operate separate Ghost publications and establish your own processes for client access, billing, permissions, provisioning, etc.

Ghost

What I'd avoid: Substack for this model

Substack is fantastic when the model is:

one publisher → one publication → one owner.

It's much less attractive when you're effectively building a newsletter-as-a-service agency with dozens of client properties, because workspace/agency administration and client separation aren't its strength. You're also giving up 10% of paid subscription revenue, which becomes significant at agency scale. letterduck.com

The architecture I'd use

For an agency, I'd actually separate client billing from your agency's software billing:

Client
→ owns Stripe account
→ owns newsletter publication
→ owns subscriber/customer data

Agency
→ gets team/admin access
→ creates content/campaigns
→ manages automations and access rules
→ charges client a separate management fee

That avoids the nasty situation where your agency technically owns all of the clients' subscribers and payment relationships.

Bottom line:

• 5–10+ newsletters under active agency management: beehiiv
• Clients demand maximum ownership/data separation: Ghost
• Simple creator publications: Substack
• Newsletter + courses/products/marketing automation: Kit

If you tell me roughly how many clients/newsletters you manage, whether each client needs their own Stripe account, and whether you're charging the clients or the readers, I can narrow this down to the best architecture and pricing model.

For an agency managing multiple clients’ paid newsletters, the key requirements are different from a normal newsletter tool:

• Separate client workspaces/publications
• Separate billing (client pays directly or you can mark up/resell)
• Role-based access control
• Subscriber ownership isolation
• Paid subscriptions/paywalls
• Revenue reporting per client
• White-label or client-facing dashboards

The best options depend on whether you are primarily a newsletter operator, publisher platform, or email marketing agency.

Best overall: beehiiv (for paid newsletter businesses)

Best if your clients are creators, media companies, or businesses running subscription newsletters.

Strengths

• Built specifically around newsletters
• Paid subscriptions and monetization workflows
• Multiple publications under larger plans
• Subscriber segmentation and analytics
• Strong publishing/growth features

beehiiv.com highlights multi-publication management, cross-publication analytics, team permissions, and enterprise publishing workflows. Beehiiv

Weaknesses

• Agency-style client billing is not its strongest area
• You may still need separate client agreements/invoicing

Best fit: An agency running 5–100+ newsletter brands as a publishing operation.

Best for agencies: Campaign Monitor

Best if you are a marketing agency managing newsletters as a service.

Strengths

• Client account separation
• Agency dashboard
• Client permissions
• Client-specific billing options
• Reporting workflows

Campaign Monitor specifically markets agency features including client account management, account-specific billing, and granular user permissions. Campaign Monitor

Weaknesses

• Less newsletter-native than beehiiv
• Paid subscription products usually require additional systems

Best fit: Agencies managing email campaigns/newsletters for brands.

Best newsletter production platform: Letterhead

Best if your agency produces newsletters for many publishers.

Strengths

• Separate client workspaces
• Brand controls/templates
• Revenue reporting
• Newsletter operations workflow

Letterhead positions itself around multi-client newsletter management with separate workspaces, brand governance, and client reporting. Letterhead

Weaknesses

• More enterprise/media focused
• May be heavier than needed for small agencies

Best fit: Newsletter-as-a-service agencies and media operators.

Best if you need maximum automation: ActiveCampaign

Best when newsletters are part of a broader customer lifecycle.

Strengths

• Deep automations
• CRM features
• Segmentation
• Client account management options

Weaknesses

• Not primarily a paid newsletter/paywall platform
• Subscription access usually needs Stripe/membership tooling

Best for a custom agency platform: Stripe + newsletter CMS + email provider

For a serious agency where each client owns their subscribers and revenue, a common architecture is:

• Stripe → payments/subscriptions
• Customer portal → client billing
• Newsletter CMS → publishing
• Email provider → delivery
• Your agency dashboard → access control/reporting

This gives you true client isolation but requires more implementation.

Quick comparison

My shortlist by agency model

• You run paid newsletters for clients and take a management fee: beehiiv Enterprise or Letterhead
• Clients hire you for email marketing services: Campaign Monitor
• You want a white-label newsletter SaaS business: custom Stripe + publishing stack
• You have fewer than ~10 clients: separate beehiiv/CMS accounts with centralized operations may be simpler

If you share roughly number of clients (5 vs 50+), whether clients pay subscribers directly or pay your agency, and whether you need white-labeling, the recommendation changes quite a bit.

My shortlist by agency model

• You run paid newsletters for clients and take a management fee: beehiiv Enterprise or Letterhead
• Clients hire you for email marketing services: Campaign Monitor
• You want a white-label newsletter SaaS business: custom Stripe + publishing stack
• You have fewer than ~10 clients: separate beehiiv/CMS accounts with centralized operations may be simpler

If you share roughly number of clients (5 vs 50+), whether clients pay subscribers directly or pay your agency, and whether you need white-labeling, the recommendation changes quite a bit.

For an agency managing multiple clients’ paid newsletters, the key requirements are a little different from a normal email marketing platform:

• Separate client workspaces (no list/data crossover)
• Separate billing or clean cost allocation
• Subscriber access control (who can read what)
• Client/team permissions
• Paid subscription handling (Stripe, memberships, paywalls, etc.)
• Reporting per client
• White-label options if you resell the service

The best fit depends on whether you are running newsletters as a service or operating a newsletter subscription business for clients.

Best options

Letterhead Campaign Monitor## My shortlist by agency model

1. You manage 10–100 client newsletters as a service

Pick: Letterhead or Campaign Monitor

These are closest to an agency operating system:

• one agency login
• separate client environments
• client-specific reporting
• controlled access
• reusable templates/workflows

Letterhead is particularly aimed at multi-client newsletter production, with separate workspaces and reporting per account. Letterhead Campaign Monitor has dedicated agency features including client account management, permissions, and client billing support. Campaign Monitor

2. Each client has a paid subscriber base

Pick: Ghost + Stripe, or beehiiv

For paid newsletters, you usually care more about:

• subscriber accounts
• paywalls
• member tiers
• cancellations/refunds
• gated archives

Ghost is strong if each client gets their own publication site. beehiiv is strong if growth, referrals, and newsletter analytics are priorities.

3. You sell “newsletter operations” as a managed service

A common agency stack:

• Client management: Campaign Monitor / Letterhead
• Payments: Stripe
• Automation: ActiveCampaign or Zapier
• Analytics: platform dashboards + client reporting tool
• CMS/membership: Ghost or Memberful where needed

What I would avoid for this use case

• Substack — excellent for individual writers, but awkward for agencies managing many independent clients.
• A single Mailchimp account with many lists — creates permission, billing, and ownership headaches.
• One shared Stripe account without customer separation — makes reconciliation and client ownership difficult.

Practical recommendation

If your agency’s core product is “we run newsletters for clients”:

1. Start with Letterhead or Campaign Monitor.
2. Add Stripe/member tooling only where clients need paid access.
3. Keep every client isolated by workspace/account from day one.

If your core product is “we build paid newsletter businesses for clients”:

1. Use Ghost or beehiiv per client.
2. Manage operations through an agency CRM/project layer.

A deciding question: are you looking for (A) one agency dashboard managing many client newsletters, or (B) a white-label platform you can resell to clients with each client having their own subscribers and billing? The best choice changes quite a bit.

1. Use Ghost or beehiiv per client.
2. Manage operations through an agency CRM/project layer.

A deciding question: are you looking for (A) one agency dashboard managing many client newsletters, or (B) a white-label platform you can resell to clients with each client having their own subscribers and billing? The best choice changes quite a bit.

If you mean an agency that operates paid newsletters for multiple unrelated clients, with each client needing isolated subscribers, billing, branding, and permissions, I’d shortlist these:

My pick: beehiiv

beehiiv is probably the best default if the core business is running newsletters, rather than general-purpose email marketing.

The important architectural point is that beehiiv supports multiple publications, but each workspace has its own billing and publications. For a client who needs their own billing, login, and ownership, beehiiv explicitly recommends putting that client in a separate account/workspace and adding your agency as a team member. www.beehiiv.comwww.beehiiv.comproduct.beehiiv.comwww.tryletterhead.com

That gives you a clean structure like:

Agency
├── Client A workspace
│   └── Newsletter A
├── Client B workspace
│   └── Newsletter B
└── Client C workspace
    └── Newsletter C

And permissions can be limited to a particular publication. Current beehiiv roles include Admin, Member, and Contributor, with publication-level access available. www.beehiiv.com

For paid newsletters specifically, beehiiv supports paid-subscriber-only email/web content and paywalls. product.beehiiv.com

The catch: if you have 20–50 clients, managing them as completely separate workspaces can become operationally cumbersome. beehiiv's multi-publication functionality is excellent when the publications belong to the same organization, but its own documentation distinguishes that from clients who need independent ownership/billing. www.beehiiv.com

If you're building an actual newsletter agency: look hard at Letterhead

Letterhead is unusually aligned with your exact use case. It markets separate governed workspaces for each client, brand controls, client-ready reporting, and an agency view that manages client workspaces from one dashboard. www.tryletterhead.com

So if your requirement is:

"I want 30 clients, but my team should be able to operate all 30 without accidentally mixing subscribers, billing, branding, or permissions."

Letterhead may actually be the more purpose-built choice.

Ghost is the best choice if clients should own everything

Ghost is compelling when your agency sets up each publication but the client should ultimately own the publication, members, and money. Ghost connects directly to the publisher's Stripe account rather than taking a platform revenue cut. ghost.org

I'd choose Ghost when clients want a more traditional owned publishing site/CMS alongside the newsletter.

What I'd choose by agency size

• 1–5 clients: beehiiv — simplest and probably best overall.
• 5–20 clients: beehiiv or Letterhead — depends on how important centralized agency operations are.
• 20+ clients: Letterhead deserves serious evaluation because the client/workspace abstraction is much closer to an agency operating model.
• Clients want maximum ownership/control: Ghost.
• You need broader CRM/marketing automation rather than a newsletter-first product: consider ActiveCampaign or HubSpot instead.

One particularly important distinction: don't put unrelated clients into one beehiiv workspace merely because it is convenient. If clients need separate billing and ownership, separate workspaces/accounts are the cleaner model. beehiiv itself recommends that approach. www.beehiiv.com

If you tell me roughly how many clients you expect (e.g. 5, 20, or 100) and whether clients need their own logins/billing, I can narrow this to the best 2–3 options and compare their current pricing and economics.

If your agency is managing multiple paid newsletters for different clients, the key requirement is not just “good newsletter software”—it’s tenant separation: each client should have its own subscribers, billing account, publication, domains, permissions, and ideally ownership.

My ranking

🥇 Best overall: beehiiv

For an agency specifically selling paid newsletters as a managed service, I'd start with beehiiv.

The important distinction is that beehiiv supports both:

Agency-owned model

Agency account → Client A publication / Client B publication / Client C publication

and

Client-owned model

Client A account → Client A publication
Client B account → Client B publication
Client C account → Client C publication
Agency gets invited into each workspace.

beehiiv explicitly documents the latter as the recommended approach when clients need their own login, billing, or full ownership. Each publication has an independent subscriber list, settings, domain, and analytics. www.beehiiv.com

The permissions are particularly useful for agencies: you can grant access at the publication level, rather than giving someone access to the entire workspace. www.beehiiv.com

And if you're operating at significant scale, beehiiv's Enterprise offering is explicitly designed around managing large multi-publication portfolios. www.beehiiv.com

The architecture I'd use:

YOUR AGENCY
│
├── Client A — separate beehiiv workspace
│     ├── Client A newsletter
│     ├── Client A subscribers
│     ├── Client A Stripe/billing
│     └── Client A domain
│
├── Client B — separate beehiiv workspace
│     ├── Client B newsletter
│     ├── Client B subscribers
│     ├── Client B Stripe/billing
│     └── Client B domain
│
└── Client C — separate beehiiv workspace
      ├── Client C newsletter
      ├── Client C subscribers
      ├── Client C Stripe/billing
      └── Client C domain

That gives you much cleaner client offboarding: the client owns the publication and revenue; your agency is simply an operator.

🥈 Ghost is arguably better if ownership is paramount

I'd choose Ghost if these are more like premium publications/membership businesses than conventional email newsletters.

Ghost has built-in paid memberships, gated content, multiple newsletters, and direct Stripe integration. Paid members are authenticated against the membership system, and billing remains in the publisher's Stripe account. Ghost takes 0% of membership revenue. docs.ghost.org

That makes this model very attractive:

Client
  ↓
Owns Ghost publication
  ↓
Owns Stripe account
  ↓
Owns subscribers + billing
  ↑
Agency has admin/editor access

It's particularly good if each client wants a website + newsletter + paywall + membership database, rather than just an email publication.

🥉 Substack: easy, but I'd avoid it for an agency

Substack is attractive because clients already understand it, but it's awkward for a multi-client agency. Critically, Substack requires a separate Stripe account for each publication; two publications can't share one Stripe account. support.substack.com

That's not necessarily bad for client separation, but it makes agency operations considerably less elegant.

What I'd actually choose

If you're building an agency around this service:

• beehiiv → best default for paid newsletter operations
• Ghost → best when clients need a serious publication/membership website
• Campaign Monitor / ActiveCampaign → better if the product is really email marketing + automation rather than a paid publication
• Substack → only when the client specifically wants Substack

One important distinction: don't put all clients' paid subscriptions under the agency's Stripe account unless you intentionally want to be the merchant of record. For most agencies, client-owned billing + agency-managed access is substantially cleaner for accounting, client ownership, refunds, taxes, and eventual offboarding.

If you tell me roughly how many clients/newsletters you're managing (e.g. 5, 20, 100+) and whether you want clients to log in themselves, I can narrow this down to the best 2–3 architectures and compare their actual pricing.

If you mean an agency that operates several clients’ paid newsletters, with each client needing its own subscribers, payments, and permissions, I’d shortlist these:

🥇 My pick: beehiiv

beehiiv is unusually well suited to this exact agency model. It explicitly supports managing multiple client publications: you can put several publications under one workspace, or give each client a separate account when the client needs their own login, billing, or ownership. www.beehiiv.com

The important distinction is:

Don't put all clients under one beehiiv workspace if clients need truly separate billing/ownership.

Instead:

Agency
 ├── Client A beehiiv account
 │    ├── Newsletter A
 │    ├── Stripe/payment setup
 │    └── Client A team
 │
 ├── Client B beehiiv account
 │    ├── Newsletter B
 │    ├── Stripe/payment setup
 │    └── Client B team
 │
 └── Client C beehiiv account
      ├── Newsletter C
      ├── Stripe/payment setup
      └── Client C team

Your agency users can then be invited into each client workspace/publication with appropriate permissions. beehiiv currently supports publication-specific access, so someone can work on A and C without automatically getting access to B. www.beehiiv.com

That's a much cleaner arrangement than trying to simulate client isolation inside one giant agency account.

beehiiv also has paid subscriptions, paywalls, Stripe-powered checkout, automated billing, and—new in 2026—group subscriptions for organizations buying multiple seats. www.beehiiv.com

beehiiv

🥈 Ghost

Ghost is my second choice if each client wants a more independently branded publication/site.

Ghost connects each publication to Stripe and supports paid memberships, subscription tiers, and content access controls. ghost.org

The downside for an agency is operational: Ghost is more naturally structured around independent publications, rather than an agency managing dozens of publications from a sophisticated multi-client control plane.

Ghost

🥉 Stripe + your own application

If you're actually building an agency SaaS rather than just choosing software for an agency, I'd consider:

Stripe Connect + your newsletter platform/backend.

Stripe Connect is specifically designed around a platform managing separate connected accounts, allowing you to keep client payment relationships separated while giving the platform centralized controls. support.stripe.com

That gives you the architecture:

Agency SaaS
      │
      ├── Client A → Stripe account A → Newsletter A
      ├── Client B → Stripe account B → Newsletter B
      └── Client C → Stripe account C → Newsletter C

It's considerably more engineering work, but gives you the strongest isolation and control.

What I'd choose

For an existing agency: beehiiv, with one workspace/account per client.

For a high-end publishing agency: Ghost is worth considering if the websites themselves matter as much as the newsletters.

For building a product that agencies use: Stripe Connect + your own access-control layer.

One particularly important requirement I'd verify before committing is who owns the Stripe account and subscriber/customer data when the client leaves the agency. That's where a lot of seemingly "multi-client" newsletter setups become painful. beehiiv's own documentation explicitly recommends separate client accounts when clients need their own login, billing, or full ownership. www.beehiiv.com

If you tell me roughly how many clients/newsletters (e.g. 10, 50, 200) and whether clients themselves need login access, I can narrow this down to the best 2–3 architectures and their likely costs.

If you mean an agency that operates paid newsletters for multiple clients, where each client should have separate subscribers, billing/revenue, domains, and permissions, I’d shortlist these:

1. beehiiv — best overall for an agency

This would be my first choice if the core product is a paid newsletter.

beehiiv explicitly supports agencies managing multiple client publications. Each publication has its own subscriber list, settings, domains and analytics, so client audiences don't get mixed. You can either run several publications in one workspace or put clients in separate accounts when the client needs their own ownership, billing and login. www.beehiiv.com

Its current Enterprise offering is particularly interesting for agencies: it supports 90+ publications, granular subscriber controls, shared templates/design systems and portfolio-level management. www.beehiiv.com

Use it when:

• You're running 5–100+ newsletters.
• Each newsletter is essentially its own publication/business.
• You want your team to operate everything centrally.
• Clients occasionally need their own workspace.
• Paid subscriptions are a major part of the business.

One important nuance: if the client must own the Stripe/billing relationship, I'd put each client in a separate beehiiv account/workspace and add the agency as a team member. beehiiv itself recommends this setup when the client needs their own login, billing or full ownership. www.beehiiv.com

2. Ghost — best if clients need a membership site too

Ghost is stronger than beehiiv when the newsletter is part of a paid content website/community.

It has proper paid/free member states, tier-based content gating and server-level protection. Payments run through the publication's Stripe account, with the publisher retaining the billing/customer data. docs.ghost.org

The downside for an agency is operational: each Ghost(Pro) publication is essentially its own site/account, so it doesn't give you beehiiv's same centralized multi-publication experience. ghost.org

Use it when: clients want:

paid newsletter + website + gated articles + memberships

rather than simply:

paid email newsletter.

3. Piano — best for enterprise publishers

Piano is the heavyweight option.

It combines subscription management, Stripe-based billing, identity management and entitlement/access control. It can gate content across websites, apps and other channels and supports sophisticated subscription products and pricing. www.piano.io

I'd consider it if your agency works with newspapers, magazines, large media brands or thousands/millions of subscribers.

For a typical newsletter agency, though, it's probably overkill.

4. NewsBox — interesting specifically for agencies

NewsBox has an unusually direct agency model: the client owns the account and subscription, while the agency receives a Manager role and operates the newsletters from its agency workflow. It explicitly advertises separate ownership, billing and access control. newsbox.comwww.beehiiv.com

That's potentially the cleanest model if your commercial requirement is:

Client owns everything → agency operates everything.

What I'd choose

For most agencies: beehiiv.

I'd structure it like this:

AGENCY
│
├── Client A — separate beehiiv workspace
│   ├── Newsletter
│   ├── Client-owned subscribers
│   ├── Client-owned billing
│   └── Agency = operator/admin
│
├── Client B — separate beehiiv workspace
│   ├── Newsletter
│   ├── Client-owned subscribers
│   ├── Client-owned billing
│   └── Agency = operator/admin
│
└── Client C — separate beehiiv workspace
    └── ...

That gives you clean client separation rather than putting 20 clients into one agency-owned account and having to untangle ownership later.

If, instead, your requirement is one agency account that can create/manage hundreds of client newsletters while each client gets isolated billing + users + permissions, I'd look much more closely at NewsBox vs beehiiv Enterprise. That's a slightly different problem from simply "multi-publication newsletter software." newsbox.comwww.beehiiv.com

If you tell me roughly how many clients (e.g. 10, 50, 500) and whether the client or agency should own the Stripe account/revenue, I can narrow this down to the best 2–3 architectures.

If your agency needs to run multiple clients’ paid newsletters while keeping each client’s billing, subscribers, ownership, and access separate, I’d shortlist these:

1. NewsBox — best match for your exact use case

NewsBox is unusually explicit about the agency/client relationship. Each client owns their organization and subscription, while the agency receives a Manager role and can manage newsletters from a centralized agency dashboard. If you stop working together, you simply lose manager access; the client keeps the publication and subscribers. newsbox.com

Current agency pricing is $199/mo for up to 5 client newsletters and $499/mo for unlimited client newsletters, with the higher tier adding white-labeling, custom domains, automated reporting, revenue-sharing tools, and API access. newsbox.com

I'd pick this if: your business model is essentially “we operate newsletters for clients, but the clients must remain the owners and pay their own platform bills.”

2. beehiiv — best mature newsletter/growth platform

beehiiv is probably the strongest alternative if the newsletters themselves need sophisticated growth, monetization, analytics, recommendations, and paid subscriptions.

It supports multiple publications, with each publication having its own subscriber list, settings, domains, and analytics. Importantly, beehiiv explicitly recommends separate accounts when a client needs their own login, billing, or full ownership, with your agency added as a team member. www.beehiiv.com

That makes the clean architecture:

Client A beehiiv account ← agency team access
Client B beehiiv account ← agency team access
Client C beehiiv account ← agency team access

rather than putting all clients into one billing account.

The downside is that the centralized agency experience isn't as purpose-built as NewsBox. beehiiv's Enterprise product is much more oriented toward companies managing their own portfolio of publications. www.beehiiv.com

3. Ghost — best if each newsletter is also a premium website/publication

Ghost is excellent when the product is more than an email newsletter: paid articles + website + membership + newsletter.

Each Ghost publication can connect directly to its own Stripe account, with Ghost taking 0% of subscription revenue. ghost.org Staff permissions are granular, ranging from Contributor through Administrator, while the Owner controls billing. docs.ghost.org

So you can give an agency editor access without giving them the client's billing credentials.

The catch: you'd generally have one Ghost site/account per client, rather than a purpose-built multi-client agency console.

4. Memberful — best if membership/access control is the hard part

Memberful is compelling if you already have an email/website stack and primarily need subscription management and entitlement/access control. It supports paid newsletter delivery, members-only web content, staff accounts, plan upgrades/downgrades, coupons, trials, and group subscriptions. memberful.com

It's more of a membership layer than an agency newsletter operating system, though.

My recommendation

For your exact requirements, I'd rank them:

🥇 NewsBox — if agency/client separation is the #1 requirement
🥈 beehiiv — if newsletter growth/monetization is the #1 requirement
🥉 Ghost — if every newsletter is really a paid publication/site
4. Memberful — if you want to assemble your own newsletter + membership stack

One particularly important distinction: don't confuse “multiple publications in one account” with true client isolation. For example, beehiiv lets you manage multiple publications together, but if clients need their own billing and ownership, beehiiv itself recommends separate accounts. www.beehiiv.com

If you're building an agency that might manage 10–100+ client newsletters, I'd lean toward separate client-owned accounts + agency-level delegated access, rather than putting all clients under the agency's master billing account. That makes client offboarding, financial reconciliation, subscriber ownership, and security dramatically cleaner.

If you mean an agency that operates multiple paid newsletters for different clients, with each client needing its own subscribers, Stripe/billing relationship, permissions, and ideally a clean handoff if they leave, I’d shortlist these:

My picks

1. beehiiv Enterprise — best if “paid newsletter” is the core product.

beehiiv is probably the strongest fit if your agency is actually running publications, rather than simply doing email marketing. Its Enterprise offering supports 90+ publications from one workspace, shared templates/content blocks, granular subscriber controls, paid/free content gating, and enterprise integrations including Stripe. www.beehiiv.com

The important distinction is that each publication has its own Stripe Express account for monetization, rather than forcing all publications into one Stripe account. beehiivhelp.zendesk.com

I'd choose this if: you have 5–100+ newsletters and want a centralized editorial/operations team.

2. Campaign Monitor — best general-purpose agency platform.

This is the strongest choice if your agency needs client isolation + agency-level management + permissions + client-specific billing more than sophisticated publisher features. Campaign Monitor explicitly supports separate client accounts, granular permissions, and account-specific pricing/billing. Its private-label options can also brand the client-facing experience. www.campaignmonitor.com

I'd choose this if: you're an email agency where newsletters are one part of a broader email-marketing service.

3. NewsBox — most interesting purpose-built agency option.

NewsBox is unusually close to your exact requirement: clients retain ownership, the agency gets Manager access, newsletters are managed from a centralized agency dashboard, and client subscription limits/billing remain attached to the client rather than the agency. It also supports white-labeling on higher tiers. newsbox.combeehiivhelp.zendesk.com

This is worth investigating if you want the agency to be an operator rather than the legal owner of every publication.

4. Ghost — best if every client should truly own their publication.

Ghost is compelling when you want each client to have an independent publishing business. Its membership system connects directly to the publication's own Stripe account, with Ghost taking no revenue share. ghost.org

The downside is that it isn't as naturally an agency multi-tenant control plane as beehiiv Enterprise or Campaign Monitor. You'd likely build some of the agency-level management/reporting yourself.

5. MailerLite — excellent practical/low-complexity option.

MailerLite now has a particularly agency-friendly model: one login can switch among separate client accounts, while each account retains its own subscribers, campaigns and billing. Its Advanced plan provides unlimited seats and granular user roles. www.beehiiv.comnewsbox.comghost.orgwww.mailerlite.combeehiivhelp.zendesk.com

It's less publisher-centric than beehiiv/Ghost, but potentially much cheaper and simpler.

What I would not use

I wouldn't make Substack the foundation for this. It's excellent for an individual publication but isn't designed around an agency's multi-client operating model.

I'd also distinguish email marketing platforms from paid-publication platforms. Campaign Monitor/MailerLite are fantastic when the agency is sending newsletters for clients. beehiiv/Ghost are better when each newsletter is itself a subscription business with paying members and gated content.

If I were building the agency today

I'd narrow it to:

beehiiv Enterprise → best overall for a portfolio of paid newsletters
NewsBox → best purpose-built agency model
Ghost + Stripe → best for maximum client ownership/control
Campaign Monitor → best conventional agency/email-marketing infrastructure

The deciding question is who should own the Stripe account and subscriber relationship. If the answer is each client independently, I'd lean strongly toward beehiiv Enterprise or NewsBox rather than trying to bolt separate billing onto a traditional ESP. newsbox.combeehiivhelp.zendesk.com

If you tell me roughly how many clients/newsletters you manage (e.g. 10, 50, 200) and whether the clients or your agency should own the Stripe accounts, I can narrow this to the best 2–3 and compare their actual pricing/architecture.

If you mean an agency that operates paid newsletters for multiple client businesses—with each client having its own subscribers, billing, and permissions—I’d shortlist these:

🥇 My pick: Audienceful

Audienceful is particularly interesting for your use case because it explicitly has separate client workspaces, with separate audiences, branding, sender identity and billing per client, while allowing the agency to switch between clients from one login. It also supports Owner/Editor/Viewer permissions. www.audienceful.com

That maps almost exactly to:

Agency → Client A workspace → paid newsletter + subscribers + billing
Agency → Client B workspace → paid newsletter + subscribers + billing
Agency → Client C workspace → paid newsletter + subscribers + billing

🥈 Campaign Monitor

Campaign Monitor is probably the safest mature agency-oriented choice. Its agency product supports separate client accounts, client-specific billing, granular permissions, reporting, and private-label/client-facing branding. www.campaignmonitor.com

I'd favor it if your operation is more like a traditional email-marketing agency than a newsletter publisher.

🥉 beehiiv

beehiiv is excellent if newsletter publishing/monetization is the core product. beehiiv explicitly supports multiple publications, each with independent subscriber lists, settings, domains and analytics. www.beehiiv.com

The important caveat: if each client must own their own billing/login/account, beehiiv recommends separate accounts with the agency added as a team member. If the agency owns everything, you can put multiple publications under one account. www.beehiiv.com

If you're building a serious agency platform

I'd consider Stripe + a newsletter engine rather than forcing the newsletter platform to solve billing.

Stripe Billing gives you subscriptions, invoices, payment methods and a self-service customer portal. Stripe also supports configurations for different customers/connected accounts. docs.stripe.com

That lets you make the architecture:

Agency
→ Client organizations
→ Newsletter/workspaces
→ Subscriber entitlements
→ Stripe customer/subscription
→ Role-based access

This is the route I'd take if you're selling the software as a managed service/white-label product rather than simply using software internally.

My ranking for your exact requirement

1. Audienceful — best all-around fit
2. Campaign Monitor — best mature agency tooling
3. beehiiv — best newsletter-native ecosystem
4. NewsBox — worth investigating specifically for agency/paid-newsletter operations; it explicitly supports client ownership, agency Manager access, and separate client billing. newsbox.com
5. Custom + Stripe — best if you're building a scalable platform rather than buying one

One important distinction: if by “separate billing and access control” you mean the newsletter's subscribers each pay separately and get access to different paid publications, rather than clients paying the agency, the recommendation changes substantially. In that case I'd put beehiiv / NewsBox / Ghost + Stripe ahead of Campaign Monitor.

If your agency manages multiple clients’ paid newsletters, with each client needing separate subscribers, billing, and access, I’d shortlist these:

1. 🥇 beehiiv — my pick

For an agency specifically running paid newsletters for multiple clients, beehiiv is probably the strongest fit.

You can put multiple client publications into an account, while each publication maintains its own subscriber list, settings, domain, and analytics. beehiiv explicitly documents this as an agency use case. www.beehiiv.com

More importantly, you can give staff access at the publication level, so someone can work on Client A without automatically getting access to Client B. Roles include Admin, Member, and Contributor, with publication-specific permissions. www.beehiiv.com

For paid newsletters, beehiiv supports paid subscriber access, paywalls, Stripe billing, subscription history, trials/promotions, and payment events. product.beehiiv.com

The catch: if each client needs to own their billing/account independently, beehiiv recommends separate accounts per client, with the agency added as a team member. www.beehiiv.com

That's actually a good architecture for an agency:

Client owns account + Stripe → Agency gets delegated access → Client's subscribers/billing stay isolated.

2. Ghost — best if ownership/control matters

Ghost is excellent if you're essentially building a separate membership publication for each client.

It has genuine paid membership infrastructure: recurring subscriptions, paid tiers, protected content, member segmentation, and granular control over which tiers can access particular content/newsletters. ghost.org

It also uses Stripe for payments and charges 0% transaction fees itself. ghost.org

I'd choose Ghost over beehiiv when the client wants a full publication/membership website, rather than primarily a newsletter-growth platform.

3. Campaign Monitor — best pure agency account management

If your key requirement is:

"I want one agency account where I manage lots of client accounts, let clients log in, and handle/resell their billing."

then Campaign Monitor deserves serious consideration.

It specifically provides agency features for client-specific billing, different client rates/currencies, and granular client permissions. www.campaignmonitor.com

Independent testing in 2026 also ranked Campaign Monitor as the strongest option specifically for multi-client agencies. hackceleration.com

The downside is that it's more of an agency email-marketing platform than a modern paid-publication/membership platform.

4. Substack — easy, but I'd avoid it for this use case

Substack lets you create multiple publications under an account and add contributors. support.substack.com

But for an agency, it doesn't give you the same clean client-account / delegated-access / billing architecture that beehiiv or Campaign Monitor does.

What I'd implement

If you're building an agency with, say, 10–50 paid newsletters, I'd use:

Client A

• Their own beehiiv account/workspace
• Their own Stripe/billing
• Their own domain
• Their own subscriber database
• Agency employees invited with publication-specific roles

Client B

• Completely separate workspace
• Completely separate billing/subscribers
• Same agency team invited as appropriate

This avoids the nasty situation where your agency owns all the clients' subscriber data and payment infrastructure. beehiiv explicitly supports this model. www.beehiiv.com

If you instead want the agency to own the entire SaaS relationship and charge clients a monthly fee, I'd look hardest at Campaign Monitor.

If you want each client to have a premium content site + newsletter + memberships, I'd choose Ghost.

If the core product is paid newsletters and audience growth, I'd choose beehiiv.

If you tell me roughly how many clients/newsletters you manage, whether clients need their own logins, and whether clients or your agency should own the Stripe accounts, I can narrow this to the best architecture and plan.

For an agency running paid newsletters for multiple clients, I’d narrow it to beehiiv vs. Ghost, with beehiiv usually the better operational fit.

1. beehiiv — best overall for an agency

This is the one I'd start with.

beehiiv explicitly supports multiple publications, with each publication having its own subscriber list, settings, domains and analytics. Its current documentation specifically discusses the use case of agencies managing newsletters for multiple clients. www.beehiiv.com

The important distinction is:

• Agency-owned workspace: put several client publications under one account for centralized operations.
• Client-owned workspace: each client gets their own account/billing/ownership, while your agency is added as a team member.
• Permissions: workspaces support roles such as Owner, Admin, Member and Contributor. www.beehiiv.comwww.beehiiv.com
• Enterprise: designed for much larger publication portfolios, with granular subscriber controls, role-based permissions and cross-publication reporting. www.beehiiv.com

That makes beehiiv particularly attractive if your agency needs to say:

"We manage 20 newsletters, but Client A must never see Client B's subscribers or billing."

For paid newsletters specifically, beehiiv also supports paid subscriptions, metered paywalls, trials and group subscriptions. www.beehiiv.com

Big caveat: if every client needs to independently own their Stripe/billing relationship and ultimately take the publication away from you, I'd use separate beehiiv workspaces/accounts per client, rather than putting everything into one agency workspace. beehiiv itself recommends that model when clients need their own login, billing or full ownership. www.beehiiv.com

2. Ghost — best for client ownership + strong membership

Ghost is compelling if your agency is essentially building and operating client-owned subscription publications.

Ghost connects directly to the client's Stripe account, so subscription revenue goes directly through their billing setup rather than through Ghost. Ghost doesn't take a transaction commission. ghost.org

It also has sophisticated membership/access concepts: multiple paid tiers, different content-access levels, member-only content and multiple newsletters with independent subscriptions/settings. ghost.org

I'd favor Ghost when your agency wants:

Client → owns Ghost publication → owns Stripe → owns subscribers/revenue → agency has admin access

That's a very clean client-services architecture.

The downside is that multi-client agency management isn't as native as beehiiv's multi-publication model. You'd generally be managing separate Ghost sites/publications rather than treating your whole client portfolio as one publishing operation.

3. Kit — good if newsletters are part of a marketing funnel

Kit makes more sense when the newsletter is one component of a client's broader creator/marketing automation system—lead magnets, sequences, products, launches, etc.

I'd put it behind beehiiv/Ghost if the core product you're selling is specifically "we operate paid newsletters for multiple clients."

4. Substack — I'd avoid for an agency

Substack is excellent for an individual publisher who wants minimal operational complexity, but its model isn't particularly agency-friendly.

You want things like:

• client-specific ownership
• isolated subscriber databases
• agency/team permissions
• client-specific billing
• easy handoff when a contract ends
• multiple publications under an agency operating model

Those requirements point much more strongly toward beehiiv or Ghost.

The architecture I'd recommend

If you're building an actual agency operation, I'd structure it like this:

Agency
→ one internal agency/admin identity
→ separate workspace/account per client
→ client owns Stripe/billing
→ client owns publication + subscriber data
→ agency gets appropriate team permissions
→ agency manages editorial, analytics and growth

That is preferable to having one giant agency account with every client's subscribers and payments mixed together, even if the software technically supports it.

For example:

Client A

• beehiiv Workspace A
• Stripe Account A
• Newsletter A
• Subscribers A
• Agency = Admin/Member

Client B

• beehiiv Workspace B
• Stripe Account B
• Newsletter B
• Subscribers B
• Agency = Admin/Member

This gives you clean offboarding: if Client B leaves, you don't have to disentangle their subscribers, billing history and publication from everyone else.

My verdict

Choose beehiiv if your agency's primary need is efficiently operating many newsletters from a centralized team, particularly if you expect dozens of clients/publications.

Choose Ghost if your primary need is building subscription publications that should remain clearly owned and billed by each individual client.

If I were designing this specifically for a 5–50 client newsletter agency, I'd probably choose beehiiv with a separate workspace/account per client, plus a standardized agency onboarding/offboarding process. That gives you the operational advantages of beehiiv without creating a nasty client-ownership/billing problem later. www.beehiiv.comwww.beehiiv.com

If you mean an agency that operates paid newsletters for multiple client companies, with each client needing its own subscribers, payments, staff permissions, and ideally ownership, I’d shortlist these:

1. beehiiv — best overall for an agency

This is probably the closest fit.

• Multiple publications: you can run each client as a separate publication, with its own subscriber list, settings, domain, analytics, and monetization. www.beehiiv.com
• Granular access: users can be restricted to particular publications, rather than seeing every client's data. www.beehiiv.comwww.beehiiv.com
• Paid newsletters: supports multiple paid tiers and paywalled content. www.beehiiv.com
• Agency scaling: Enterprise is explicitly designed for organizations managing many publications, including 90+ publications. www.beehiiv.com
• Important billing caveat: if the client should own the billing account and publication, beehiiv recommends putting that client in their own account and adding your agency as a team member. www.beehiiv.com

Best setup: one beehiiv account/workspace per client when clients need independent ownership and billing; your agency gets invited access.

2. Ghost — best if each client needs a truly independent publication

Ghost is excellent for paid membership/newsletter businesses, but it's less convenient for an agency operating dozens of clients centrally.

Each Ghost publication can have multiple newsletters with separate subscription settings, and Ghost supports paid subscriptions through Stripe. ghost.org

The catch is significant: each independent Ghost(Pro) site requires its own Ghost(Pro) account/subscription. ghost.org

So I'd choose Ghost when client independence/ownership matters more than centralized agency operations.

3. Stripe Connect + a newsletter platform — best for a custom agency platform

If you're actually building an agency SaaS/platform, rather than just choosing software for your own agency, this is the architecture I'd investigate.

Stripe Connect is designed for platforms that manage payments for multiple businesses/connected accounts, and Stripe supports centralized management while keeping accounts separate. stripe.com

You could have:

Agency
→ Client A workspace → Client A Stripe account → Client A newsletter
→ Client B workspace → Client B Stripe account → Client B newsletter
→ Client C workspace → Client C Stripe account → Client C newsletter

That gives you a much cleaner separation of money, ownership, customer records, and permissions than trying to make one Stripe account serve every client.

My recommendation

Bottom line: For an agency managing clients today, I'd start with beehiiv, using one client = one publication/account when the client needs independent billing and ownership. Its current permission model is unusually well suited to separating agency staff by publication. www.beehiiv.comwww.beehiiv.com

If by “separate billing” you mean the agency charges each client a monthly management fee, rather than each client independently charging their newsletter subscribers, that's a different architecture—and I can recommend the best stack for that specifically.

If you're an agency running paid newsletters for multiple clients, I’d shortlist these:

1. beehiiv — best overall for an agency

This would be my first choice.

beehiiv explicitly supports agencies managing multiple client publications. One workspace can contain multiple publications, with each publication having its own subscriber list, settings, domain and analytics. Current limits are up to 3 publications on Launch/Scale, 10 on Max, and custom numbers on Enterprise. www.beehiiv.com

More importantly for your use case, you can either:

• Put multiple clients under your agency workspace, or
• Give each client their own beehiiv workspace/account and join it as a team member.

The latter is preferable when the client needs their own billing, login and ownership. www.beehiiv.com

For access control, beehiiv has publication-level and workspace-level roles, so you can give an editor access to Client A without exposing Client B. www.beehiiv.com

For the subscriber side, it supports multiple paid tiers, Stripe billing, paywalls, paid-only email/web content, and tier-specific access. beehiivhelp.zendesk.com

Best architecture:
Agency team → separate beehiiv workspace per client → client's Stripe account → client's publication

That keeps ownership and money cleanly separated while still letting your agency operate everything.

2. Ghost — best if you want maximum ownership/control

Ghost is particularly attractive if each client wants a more substantial publication/site rather than "just a newsletter."

Ghost has native memberships, paid subscriptions, member-only content, paid tiers and newsletters. Billing can connect directly to the client's Stripe account, with Ghost taking 0% of subscription revenue. ghost.orgdocs.ghost.org

Its access model is also strong: content can be public, members-only, paid-members-only, or restricted to particular tiers. ghost.orgdocs.ghost.org

Downside for an agency: it's less purpose-built around the "one agency, dozens of client publications" workflow than beehiiv. You'll generally manage each client's Ghost site separately.

3. Substack — easiest, but weakest for agencies

Substack allows multiple publications under one account, so you can switch between client publications from the dashboard. support.substack.com

But I wouldn't choose it for a serious agency operation where client ownership, granular staff permissions, separate billing and operational separation are important. It's optimized much more for individual publishers than agencies.

My recommendation

If your agency manages, say, 5–50 paid newsletters, I'd choose beehiiv.

I'd structure it like this:

Client → owns workspace + Stripe account
↓
Agency → invited as Admin/Member with only necessary permissions
↓
Publication → client's newsletter + subscriber database + paid tiers
↓
Stripe → client's billing/revenue

That gives you a clean separation between client data, subscriber access, payments and agency staff.

If you're expecting 50+ clients, or need things like white-label client portals, centralized agency billing, consolidated reporting across clients, client approval workflows, and one login for your operators, I'd look beyond newsletter-native platforms and consider an agency-oriented stack built around Stripe + a membership/auth layer + an email delivery platform. That can be substantially more flexible than trying to force one newsletter SaaS to behave like a multi-tenant agency platform.

If you tell me roughly how many clients you manage and whether clients need to log in themselves, I can narrow this down to the best 2–3 architectures.

For an agency managing multiple clients’ paid newsletters, I’d shortlist these:

My pick: beehiiv

For your exact use case, beehiiv is probably the best fit.

It explicitly supports agencies managing multiple client publications. You can either:

• Put multiple client publications in one workspace, with each publication having its own subscriber list, settings, domain and analytics; or
• Give each client their own beehiiv workspace/account, with the agency added as a team member. The latter is the better architecture when clients need their own login, billing, and ownership. www.beehiiv.com

Its current permissions are particularly useful for agencies: you can give someone access to only specific publications, rather than exposing every client's data. Roles include Admin, Member, and Contributor, with publication-level access. www.beehiiv.com

For larger agencies, beehiiv Enterprise is designed around multi-publication management and offers role-based permissions, portfolio analytics, and custom publication limits. www.beehiiv.com

Recommended setup:

Client A → Client A beehiiv workspace → Client A Stripe/billing
Client B → Client B beehiiv workspace → Client B Stripe/billing
Agency → invited into each workspace with appropriate permissions

That gives you clean billing separation + subscriber-data isolation + client ownership, while your agency can operate all the accounts.

Ghost is the better alternative if you need a full membership website

Ghost is particularly strong if each newsletter is really a paid publication/site, rather than just an email newsletter. It has native paid memberships, gated content, multiple tiers, and direct Stripe integration. Payments go directly to the publication's Stripe account and Ghost takes 0% transaction revenue. ghost.org

I'd choose Ghost when clients want things like:

• paid articles/archive
• member-only websites
• multiple subscription tiers
• custom websites
• full ownership of their Stripe/customer data

I wouldn't make Substack the agency standard

Substack does support multiple publications under one account, but its model is more oriented toward individual publishers than an agency operating a portfolio of client businesses. support.substack.com

Bottom line:
beehiiv for an agency operating many client newsletters; Ghost for agencies building full paid membership publications.

If you tell me roughly how many clients you manage (e.g. 5, 20, 100+) and whether each client needs to own/pay their own Stripe account, I can narrow this down to the best architecture and plan tier.