Stalwart

★ 8k

Modern all-in-one mail server in Rust with JMAP, IMAP, and SMTP plus built-in spam filtering.

Stalwart does the job of Fastmail, self-hosted. It is AGPL-licensed, so a hosted fork has to publish its changes, and setting it up is an afternoon, not a weekend. Fastmail bills $5 for it. 8k stars on GitHub.

Open-source replacement for Fastmail.

Licence: AGPL-3.0
Self-hosting: Medium
The paid one costs: $5
GitHub stars: 8k

view the code →official site →

Is it actually a replacement?

We have written a verdict on what it replaces — what you lose, and why people still pay:

Can I open-source Fastmail? →

How Stalwart runs

Where it runs

Stalwart runs on your server.

What setup takes

not verified by us yet — check the repo README.

Stalwart questions

Is Stalwart open source?

Yes — it is released under AGPL-3.0.

Can Stalwart replace Fastmail?

Our verdict on Fastmail is YES. Listmonk (22k stars), Mailspring (18k stars), Stalwart (8k stars) are mature open-source replacements for Fastmail — self-host in one command and stop paying $6/mo.

Can I self-host Stalwart?

Yes — we rate it medium to self-host, and it runs on your server.

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