MailFlow is switching to a dual license: AGPL-3.0 + Commercial

[maathimself]

Hey everyone,

I wanted to be upfront about a change I'm making to how MailFlow is licensed, explain why, and make clear what it means for you.

What's changing

MailFlow is moving from MIT to a dual-license model:

• AGPL-3.0 (free) — for personal use, self-hosting, and open-source projects
• Commercial license ($500/install, one-time) — for businesses or deployments where AGPL obligations can't be met

Personal self-hosting is free and always will be. If you're running MailFlow for yourself, your family, or a non-commercial project, nothing changes for you.

Why

I have been putting, and will continue to put a significant amount of time/money into building and maintaining MailFlow. MIT allowed anyone — including businesses — to take the code, build commercial products on top of it, and give nothing back. That's not sustainable for a solo developer.

This change doesn't affect the people MailFlow was built for. It just means that if a business wants to use MailFlow commercially, they contribute something back instead of getting a free ride.

What AGPL means in practice

If you self-host MailFlow for personal or internal non-commercial use, AGPL has no meaningful impact on you. The main obligation only applies if you modify and distribute MailFlow or offer it as a hosted service — in that case, you'd need to publish your changes. Most self-hosters will never hit this.

Commercial license

If your use case requires a commercial license, it's a one-time $500 per installation. You can purchase it here.

Contributing

Going forward, pull requests require agreeing to the Contributor License Agreement. It's straightforward — you keep copyright over your work, you just grant me the right to include it in both the open-source and commercial versions. The checkbox is built into the PR template.

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Thanks for using and supporting MailFlow. Happy to answer any questions below.