Mailspring

Last reviewed Aug 26, 2026 · 858 words

Nothing about Mailspring goes on your server. It is an Electron desktop app for Windows, macOS and Linux that talks IMAP and SMTP to whatever mail server you already run, and its place in a self-hosted stack is the laptop end of the connection. The reason it shows up in a self-hosting directory at all is that it is one of the few modern-looking clients that treats a plain IMAP server as a first-class citizen rather than a fallback, and that it pairs well with the kind of mail server you would host yourself. The catch is that a couple of its headline features are not local at all.

Where it sits: the client end of your own mail server

Self-hosted email is two problems, and the honest self-hosted email guide covers the hard one, the server. Once you have Stalwart or a Postfix and Dovecot pair running, you still need something on the desk that reads it, and the webmail that ships with most servers is fine but rarely pleasant. Mailspring's sync engine is a native C++ process bundled with the app that mirrors your IMAP folders into a local SQLite database, so searching 10 years of mail is instant and the app works offline. Add an account, pick "IMAP / SMTP" from the provider list, enter the hostnames and ports (993 and 587 or 465 in the usual setups), and it behaves like a first-party client for your server. It handles several accounts in a unified inbox, threads conversations properly, and the interface has kept up with what Gmail trained people to expect: snooze, send later, templates, a reminder when nobody replies.

What runs on your machine and what does not

Mail sync, search, the database and composing are local. The features that are not: read receipts and link tracking work by routing through Mailspring's servers, because that is how a tracking pixel has to work; the "send later" and reminder features have historically been handled by their cloud too. None of that touches your message bodies for ordinary sending, but if you have gone to the trouble of self-hosting mail to keep it off other people's infrastructure, turn tracking off and treat those features as not for you. At last check the app also asks you to create a Mailspring ID on first launch, which is what ties Pro features to you; it can be skipped, and the core IMAP client works without an account.

The catalogue's "Electron memory usage" con is fair. Budget 512 MB of RAM with one account open and more with several large ones. It is not a problem on a modern laptop and it is a real one on a 4 GB machine.

Pro is a subscription, and most people do not need it

The free tier includes unlimited accounts, the unified inbox, snooze, undo send, themes and the local search. Pro, at about 8 dollars a month at last check, adds the tracking features, more templates, contact and company profiles in the sidebar, and a few power-user extras. For someone self-hosting mail to avoid recurring fees, the free tier is the product. The app is GPL-3.0 and the client is fully open source; the Pro services are the company's hosted half.

Thunderbird and the alternatives

The obvious comparison is Thunderbird, which is not in this directory but is the client most self-hosters actually run. Thunderbird wins on calendar and contacts (CalDAV and CardDAV built in, which Mailspring does not do), on extension count, on PGP support, and on not needing any account with anyone. Mailspring wins on looks, on speed of the initial sync and search, and on the newcomer-friendly features. If you also self-host calendars and contacts through your mail server or Nextcloud, Thunderbird's integration is the deciding factor and I would pick it. If email is the only thing and you want it to feel like a 2026 app, Mailspring is the nicer daily driver. Either way the server side is unchanged, and the email category is where that decision lives.

Two practical notes for self-hosted servers. Mailspring supports self-signed certificates only grudgingly, so put a real Let's Encrypt certificate on your IMAP and SMTP ports before adding the account; it saves an hour of confusing errors. And the initial sync of a large mailbox is heavy on the server, so add accounts one at a time if you are on a small VPS.

What I'd do

Run Mailspring on the desktop against a self-hosted IMAP server with a proper certificate, skip the Mailspring ID or ignore it, and never enable read receipts or link tracking. Stay on the free tier. If you need calendar and contacts in the same window, use Thunderbird instead and lose nothing that matters. Mailspring is the client I recommend to people who tried Thunderbird and bounced off the interface, and for them it is the difference between using their self-hosted mail and drifting back to Gmail.