JPG attachments have..txt extension added

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

23

Where did you get the app from?

Google Play

Android version

16

Device model

Samsung Galaxy S23 ultra

Steps to reproduce

1. Open mail with image attachment
2. Try to open attachment to view image
3. A selection of apps is offered to open the attachment which is not seen as a jpg
4. Download the attachment. It has a double extension of . jpg.txt asked cannot be opened as is.

Expected behavior

The app should retain the original file extension and show the image or download correctly to be viewed.

Actual behavior

The image cannot be viewed without changing the file extension.

Logs

The email forwarded to another email does not have this extension added. The webmail original doesn't either. both contain attachments with correct file extensions.

Reproduce the problem in Thunderbird for Android 23 on Android 16 using a mail with a JPG attachment, then trace the attachment download and open flow. Done means the attachment keeps its original JPG extension, is recognized as an image, and can be viewed or opened without renaming it.