Where Does K-9 Mail Store Settings and Backups?
K-9 Mail private data on Android is not browsable, so backup means the .k9s export file.
Last updated
K-9 Mail (now Thunderbird Android) keeps accounts, cached mail and prefs in app private storage (/data/data/com.fsck.k9), invisible to file managers without root and wiped on uninstall or Clear Data.
Backup is an export flow: Settings, Backup, Export settings writes a .k9s file to a folder you pick, reimported the same way with per account selection. The file carries configuration only, never passwords, so reenter those on the new device and let mail resync over IMAP.
Where K-9 Mail stores this, by platform
/data/data/com.fsck.k9/
App private storage: accounts, message cache, databases, prefs. Not browsable without root. Back up via Settings, Backup, Export settings to a user chosen .k9s file; import the same way. Export holds no passwords.
Frequently asked questions
How do I move K-9 Mail to a new phone?
Export settings to a .k9s file, copy it across, and import under Settings, Backup. Reenter passwords when prompted; mail itself resyncs over IMAP afterward.
Does the K-9 export include my passwords?
No. The .k9s file holds accounts and settings only. Keep a password manager handy for the move, since every account asks again on first sync.
Notice an outdated path? Let us know.