Fix Mail.app crashing in macOS High Sierra – remove and rebuild Envelope Index files

Since upgrading to the very first public beta of macOS High Sierra, I was encountering an issue with Mail.app crashing after a few minutes – and since the crashes were still persistent in the most recent 10.13 Beta (17A358a), I started looking into it myself, rather than waiting for another beta release to fix this.

With success: I was able to fix my Mail.app crashing continuously in macOS High Sierra by rebuilding Mail’s Envelope Index files.

How to fix Mail.app crashing in macOS High Sierra after upgrade

Turns out that after the OS upgrade, the Mail.app indexes were broken and causing it to crash. Time to rebuild them:

1. Quit Mail.app in case it’s running
2. Go into the MailData folder (using CMD+G in Finder) located at
   ~/Library/Mail/V5/MailData
   
3. Move the following files to the Trash (or to your Desktop, in case you want to backup)
   • Envelope Index
   • Envelope Index-shm
   • Envelope Index-wal

   

4. That’s it – now restart Mail.app & confirm to rebuild the index (this might take a while…)

Once done, Mail.app should run without crashing anymore. Kudos to this old Apple-Holic article over at computerworld.com for describing the procedure!