Open source email marketing software

Open source email marketing software in 2026 — and the source-available option without the AGPL trap

When people search for "open source email marketing software," they usually mean: own the code, self-host it, and stop paying a per-subscriber fee. The genuinely open-source options that fit that are listmonk, Mautic, Keila, phpList, and Mailtrain. This guide is honest about them — including the one catch most listicles skip: their AGPL/GPL copyleft, which restricts reselling a modified version as a service. If that's your plan, there's a source-available route (AcelleMail) that ships the full source without the copyleft. Here's the straight comparison.

Try the live demo

Open source vs source-available — the distinction that matters

Open source (OSI licences like AGPLv3 and GPLv3): the code is free and public, anyone can use and redistribute it. The catch is copyleft — distribute a modified version, or under AGPL offer it as a network service, and you must publish your changes under the same licence. For self-hosting your own newsletters that's a non-issue; for building a proprietary or white-label product on top, it's a real constraint (many companies treat AGPL as a non-starter for commercial software).

Source-available (how AcelleMail ships): you get the full, unencrypted source under a commercial licence — read it, modify it, and on the Extended licence resell it — with no copyleft. It is not free and not OSI open source. The trade is simple: $0 + community code with copyleft, versus a one-time fee for owned source you can keep proprietary and resell.

Open-source email marketing tools, compared honestly

Tool	Licence	Source ships?	Resell as SaaS?	Price	Hosting	Builder
AcelleMail	Source-available (commercial)	Yes (PHP)	Yes — no copyleft	One-time $80 / $199	Low–medium	Drag-and-drop
listmonk	AGPLv3 (OSI)	Yes (Go)	Restricted (copyleft)	Free	Low (binary)	Template / HTML
Mautic	GPLv3 (OSI)	Yes (PHP)	Restricted (copyleft)	Free	High	Builder
Keila	AGPLv3 (OSI)	Yes (Elixir)	Restricted (copyleft)	Free (+ Cloud)	Medium (Docker)	Builder
phpList	AGPLv3 (OSI)	Yes (PHP)	Restricted (copyleft)	Free	Medium	Basic
Mailtrain	GPL (OSI)	Yes (Node.js)	Restricted (copyleft)	Free	Medium	Basic

"Resell as SaaS?" reflects the licence's copyleft, not a technical limit. Facts from each project (2026) + the AcelleMail codebase. Background: why many companies avoid AGPL.

The open-source options, reviewed

listmonk (AGPLv3)

A single Go binary on PostgreSQL — the lightest, fastest open-source option for broadcast lists. Automation is minimal and it's single-tenant. The cleanest pick for a developer self-hosting their own newsletters.

Mautic (GPLv3)

A PHP/Symfony marketing-automation platform with the deepest open-source visual campaign builder. Powerful, but the heaviest to install and operate of this group.

Keila (AGPLv3)

A newer Elixir app, 100% open source, with an official Docker image and an EU-hosted "Keila Cloud". Sends via SES/SMTP/Mailgun/Postmark/SendGrid, with segments, automations, and A/B testing — explicitly a Mailchimp alternative.

phpList & Mailtrain

phpList (AGPLv3, PHP) and Mailtrain (GPL, Node.js) are veteran free, self-hosted newsletter apps — dependable for lists + SMTP/SES sending, but more basic on builder and automation.

Where AcelleMail fits — the AGPL reseller problem, solved

AcelleMail is not open source, and this page won't pretend otherwise. It's a source-available PHP/Laravel app on a $80 one-time licence with the full, unencrypted source. What it adds over the free options is breadth (drag-and-drop builder, visual branching automation, A/B testing, segmentation, 8 sending drivers, an 18-locale UI) and — the point of this page — a clean reselling path.

If you want to run email marketing as a service for clients, the AGPL/GPL tools put copyleft obligations in your way the moment you offer a modified version. AcelleMail's Extended licence ($199) gives you a multi-tenant SaaS layer — customer accounts, plans, 6 payment gateways, dunning, white-label — on a commercial licence with no copyleft. You own the source, keep your changes private, and resell it as your own product. That's the gap the free open-source tools structurally can't fill.

The self-hosting reality check

Open source or source-available, self-hosting means you run the server and own deliverability. Budget for a small VPS (or Docker), a sending account (Amazon SES at ~$0.10 per 1,000), DNS records (SPF/DKIM/DMARC), and your time on setup and updates. The payoff is no per-subscriber fee and full control of your list and data. If that operational load isn't for you, a hosted SaaS stays managed — at a recurring cost.

Try the live demo

Open source email marketing — frequently asked questions

Is there a truly open-source email marketing platform?

Yes. listmonk (AGPLv3, Go), Mautic (GPLv3, PHP), Keila (AGPLv3, Elixir), phpList (AGPLv3, PHP), and Mailtrain (GPL, Node.js) are all OSI-licensed open source — free to download, full code public on GitHub, self-hosted. They differ in stack, automation depth, and how easy they are to operate, but each is a genuine open-source email marketing tool.

Is AcelleMail open source?

No — and it's worth being precise. AcelleMail is source-available, not OSI open source: the full, unencrypted PHP source ships to you under a commercial CodeCanyon licence, but it is not free and it is not published under an open-source licence. If you specifically need an OSI-approved, $0 licence, the open-source options above are the right fit. AcelleMail is for buyers who want to own and modify the source — and resell it — without the copyleft obligations those licences carry.

What is the difference between open source and source-available?

Open source (OSI licences like AGPLv3/GPLv3) means the code is free and public, anyone can use and redistribute it — but copyleft licences require that if you distribute a modified version, or in AGPL's case offer it as a network service, you publish your modifications under the same licence. Source-available means you receive the full source under a commercial licence with NO such obligation — you can read, modify, and (with AcelleMail's Extended licence) resell it as a closed product. The trade is cost ($0 vs a one-time fee) versus freedom to keep your changes and your SaaS proprietary.

Can I run an open-source email tool as a SaaS for clients?

Technically yes, but read the licence first. listmonk, Mautic, Keila, phpList, and Mailtrain are AGPL/GPL — running a modified version as a service to others can trigger source-availability obligations (especially under AGPLv3, which is written specifically to cover network use). Many companies treat AGPL as a non-starter for commercial products for exactly this reason (see opencoreventures.com on the AGPL). If reselling is your goal, AcelleMail's Extended licence ($199) gives you a clean, no-copyleft path with a built-in multi-tenant billing layer.

What does AGPL mean for my business?

AGPLv3 extends GPL copyleft to cover software offered over a network: if you modify an AGPL app and let others use it as a service, you may have to release your modified source under AGPL. For self-hosting your own newsletters that is rarely an issue. It becomes a real constraint if you plan to build a proprietary product or a white-label SaaS on top of it. That single clause is why teams reselling email marketing often choose a commercial source-available licence over a free AGPL tool.

Which open-source email marketing tool is best?

For the lightest footprint, listmonk (a single Go binary). For the deepest automation, Mautic. For a modern, EU-hosted, 100% open-source option, Keila. phpList and Mailtrain are veteran free choices for simpler needs. Match the tool to your priorities — footprint, automation, or stack — and budget for the hosting and deliverability work you take on by self-hosting.

Are open-source email marketing tools really free?

The software licence is free, but running it is not zero-cost: you pay for a server (a small VPS, cPanel host, or Docker), a sending service (Amazon SES is the usual choice at ~$0.10 per 1,000 emails), and your own time on setup, deliverability, and updates. The total is still far below a per-subscriber SaaS at scale — that's the appeal — but "free" means free of licence fees, not free of operating cost.

Do I need to be a developer to run one?

Not necessarily, but some technical comfort helps. listmonk is a single binary; Mautic, Keila, and AcelleMail ship installers or Docker images; all need DNS records (SPF/DKIM) and a sending account. You don't have to write code, but you do manage a server and deliverability. If that's not for you, a hosted SaaS keeps it managed — at the cost of a recurring fee and not owning the software.

Open source vs AcelleMail — which should I choose?

Choose a free OSI tool (listmonk, Mautic, Keila) if a $0 licence and community-developed code matter most and you self-host for your own use. Choose AcelleMail ($80 one-time) if you want a fuller bundled app — drag-and-drop builder, visual automation, multi-tenant SaaS — with the full source you can modify privately and resell without copyleft. Both let you own your data and avoid per-subscriber pricing; the deciding factor is licence freedom-to-resell vs zero cost. Try the live demo first.