
Ellie Kennard
There seems to be a bug in the app where JPG attachments have a .txt extension added. This gives something like photo.jpg.txt which file is not able to be viewed, obviously until it's downloaded and the .txt extension is removed by the user. It seems to be applied when the option to either download or view the file is chosen. That same file on the email on Windows Thunderbird does not have this problem, and if that email is forwarded to something like gmail, the attachment is normal.
45 people found this review helpful
Mozilla Thunderbird
September 15, 2026
Thanks so much for reporting this, and we very much want to investigate this issue with JPG attachments further. Can you please open a bug report with any useful information at github.com/thunderbird/thunderbird-android/issues for our bug triage volunteers and developers? Thanks!

Michael Burns
Desktop version is great and I have used it since inception. The Android app is just a warmed over k9 mail, and still has all of k9's deficiencies. Two glaring ones are no support for filtering messages (for example to automatically sort incoming mail) and the other, related one, is no autoresponder support. The desktop version has excellent filteration and the filters can be used to set up autoresponses based on details of the message. A curious failure.
26 people found this review helpful
Mozilla Thunderbird
July 7, 2026
Unfortunately the Android app doesn't support filters yet. This could be something we add in the future, though we don't know when. For now, please upvote and support requests for filters at connect.mozilla.org

Codey Jackson tax
this app has been a real let down so far. I'm a long time Thunderbird desktop user and I've been waiting on an Android version for years. I've been using this for a few months now and I'm about ready to go back to my phone's default email app. I'm constantly having emails not send and the UI really could be better. hopefully improvements come later.
2 people found this review helpful
Mozilla Thunderbird
September 8, 2026
While we are working on improving and refactoring our message sync, be sure to check your app has unrestricted battery access to enable background sync! You can check this by long pressing the app icon, tapping the info icon, and tapping 'Battery'