I see no options to disable automatic updates. I have installed an older version…one that doesn’t have spell check or address book problems. Unfortunately the program auto updates & the bugs return.
If we could use an older version, maybe we could get functionality back.
There’s no in-app switch to turn off updates, but there are ways to hold a version, and they’re written up here: Can I turn off automatic updates or use an older version? — Mailspring Documentation. On Windows and macOS the app checks updates.getmailspring.com in the background and installs the new version at the next restart, so blocking that host in your firewall or hosts file stops it (on macOS you can also make the app read-only with chmod -R a-w /Applications/Mailspring.app). On Linux, the .deb and .rpm builds never install updates themselves - they only show a “Download Now” notification. Every past release is available under Releases on the GitHub project if you want to step back.
That said, this post is from the 1.10 era and the spell check and address book problems you were hitting have had a lot of releases of fixes since then. I’d much rather you tried the current 1.24.x build and told me what’s still broken than pinned an old one - old releases miss security fixes, and provider sign-in changes (Google and Microsoft in particular) tend to break them over time.