Mailspring seems to store email attachments under (in Linux, Debian) ~/.config/Mailspring/files. It seems that files stay there even after emails are deleted and also after using “Reset Cache” under the “Local Data” section in the “General” tab of the Preferences.
Is there a way to remove the unnecessary files from within Mailspring?
Extra question: Wouldn’t this be the desired behavior of the Local Data/Reset Cache option?
You’ve read it right: Reset Cache deletes only the mail database (edgehill.db) and leaves ~/.config/Mailspring/files alone, and the sync engine never prunes that folder on its own — it only expires old message bodies from the database, not the attachment files that came with them. files/ grows until you clear it yourself.
Safe way to reclaim the space: quit Mailspring completely (including the tray icon), delete the files folder, then start Mailspring and run Preferences > General > Reset Cache (or Rebuild Cache… on the individual account under Preferences > Accounts). Doing both together matters: if you delete files/ on its own, messages whose bodies are already cached won’t re-download their attachments, and opening one will fail until that message is re-fetched. Resetting the cache re-downloads bodies and attachments consistently for recent mail.
And I agree Reset Cache should probably clear the attachment folder as part of the job. Docs for the cache options are here: Clearing the Mailspring cache — Mailspring Documentation