The mailcow team published its Mooctober 2026 release on October 21, 2026, tagged as a security update. It bundles three component upgrades: PHP 8.2.35, SOGo 5.12.12 and Nginx 1.30.6. On the PHP side, the release notes also mention that the base image moves to Alpine 3.24 and that PECL extensions are now built from GitHub.
Beyond the security work, the release includes a UI update and two rounds of translation updates pulled in from Weblate. A full changelog comparing the previous 2026-09a tag with 2026-10 is linked from the release page.
Who this affects
Anyone running mailcow-dockerized, whether on a single home server or a small production mail host. Because this is flagged as a security update, it deserves a place on your maintenance schedule rather than sitting in the backlog until the next convenience window. The PHP base image change is the part most likely to matter beyond the version numbers: rebuilding on a new Alpine base and compiling PECL extensions from GitHub changes how the image is assembled, so it is worth watching the build output on your first pull.
Why it matters
Mail servers are exposed services. They accept connections from the outside world, handle authentication and hold mailboxes full of other people's messages. Keeping the web tier, the groupware layer and the PHP runtime current is basic hygiene, and upstream calling this a security update is a clear signal about intent. The translation and UI changes are pleasant, but they are not the reason to act.
Commentary for self-hosters
Treat this like any other mailcow bump: read the release notes, check the full changelog, take a backup of your configuration and volumes, then update in a quiet window. If you pin image tags, bump them deliberately instead of relying on a floating tag. After the update, verify that webmail and SOGo logins work, that mail flows in and out, and that your reverse proxy still talks to the new Nginx cleanly. If you run add-ons against the mailcow API, give them a quick smoke test too; that is where small component changes tend to surface first.
If you would rather spend the evening on features than on the upgrade, our mailcow Toolkit is built for people running mailcow in self-hosted setups.
The release is available on GitHub: mailcow-dockerized 2026-10.