Link within email not actioned

Can you run the following command in a terminal, and share the output here?

    find ~/.thunderbird -name handlers.json -print -exec cat '{}' \;

find ~/.thunderbird -name handlers.json -print -exec cat '{}' \;
/home/tony/.thunderbird/mmhujxko.default/handlers.json
{"defaultHandlersVersion":{},"mimeTypes":{"application/pdf":{"action":3,"extensions":["pdf"]},"audio/x-wav":{"action":2,"handlers":[{"name":"kaffeine","path":"/usr/bin/kaffeine"}],"extensions":["wav"]},"image/jpeg":{"action":2,"handlers":[{"name":"gwenview","path":"/usr/bin/gwenview"}],"extensions":["jpeg","jpg","jpe"]},"application/zip":{"action":4,"extensions":["zip"]},"application/msword":{"action":4,"extensions":["doc","dot"]},"application/vnd.openxmlformats-officedocument.wordprocessingml.document":{"action":4,"ask":true,"extensions":["docx"]},"application/vnd.ms-excel":{"action":4,"ask":true,"extensions":["xls","xlb","xlt"]},"audio/vnd.wave":{"action":4,"ask":true},"image/tiff":{"action":2,"ask":true,"handlers":[{"name":"GNU Image Manipulation Program","path":"/usr/bin/gimp-2.8"}],"extensions":["tif","tiff"]},"application/x-xpinstall":{"action":2,"ask":true,"handlers":[{"name":"Thunderbird Mail","path":"/usr/bin/thunderbird"}],"extensions":["xpi"]},"image/png":{"action":2,"ask":true,"handlers":[{"name":"Okular","path":"/usr/bin/okular"}],"extensions":["png"]},"application/rtf":{"action":4,"ask":true,"extensions":["rtf"]},"application/vnd.oasis.opendocument.text":{"action":4,"ask":true,"extensions":["odt"]},"text/plain":{"action":2,"ask":true,"extensions":["txt","asc","text","pot","brf","srt"],"handlers":[{"name":"Kate","path":"/usr/bin/kate"}]},"application/vnd.ms-word.document.macroenabled.12":{"action":4,"ask":true,"extensions":["docm"]},"application/vnd.oasis.opendocument.spreadsheet":{"action":4,"ask":true,"extensions":["ods"]},"image/*":{"action":0,"ask":true,"handlers":[{"name":"gwenview","path":"/usr/bin/gwenview"}],"extensions":["jpg","jpeg","jpe"]},"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":{"action":4,"ask":true,"extensions":["xlsx"]},"application/vnd.openxmlformats-officedocument.presentationml.presentation":{"action":4,"ask":true,"extensions":["pptx"]}},"schemes":{"http":{"action":2,"handlers":[{"name":"Firefox Web Browser","command":"env %u"},{"name":"thunderbird","path":"/usr/bin/thunderbird"}]},"https":{"action":2,"handlers":[{"name":"Firefox Web Browser","command":"env BAMF_DESKTOP_FILE_HINT=/var/lib/snapd/desktop/applications/firefox_firefox.desktop /snap/bin/firefox %u"}]}}}

The value "2" for the "action" entry for both "http" and "https" indicates that thunderbird should use a custom application to handle the links, instead of the system default (that would be value "4"). Is there a good reason for this configuration, or would it be reasonable to delegate opening http and https links to your desktop environment's default browser?

Thank you for responding. I wasn't aware that this was the setting. I would have assumed that it did use the desktop default.

I've been doing some searches to work out how to reset this setting without success and would welcome any pointers.

If you open Thunderbird's preferences, in the General tab there is a "Files & Attachments" section where you should be able to reset these settings.

Outcome slightly weird.

Under "Files & Attachments" there was an entry for content type http. The only options were "Always ask" or "Use Konqueror (default)". I chose Konqueror and now http links in emails open in Firefox!

There is no entry for https and https links do not open in anything.

/home/tony/.thunderbird/mmhujxko.default/handlers.json
{"defaultHandlersVersion":{},"mimeTypes":{"application/pdf":{"action":3,"extensions":["pdf"]},"audio/x-wav":{"action":2,"handlers":[{"name":"kaffeine","path":"/usr/bin/kaffeine"}],"extensions":["wav"]},"image/jpeg":{"action":2,"handlers":[{"name":"gwenview","path":"/usr/bin/gwenview"}],"extensions":["jpeg","jpg","jpe"]},"application/zip":{"action":4,"extensions":["zip"]},"application/msword":{"action":4,"extensions":["doc","dot"]},"application/vnd.openxmlformats-officedocument.wordprocessingml.document":{"action":4,"ask":true,"extensions":["docx"]},"application/vnd.ms-excel":{"action":4,"ask":true,"extensions":["xls","xlb","xlt"]},"audio/vnd.wave":{"action":4,"ask":true},"image/tiff":{"action":2,"ask":true,"handlers":[{"name":"GNU Image Manipulation Program","path":"/usr/bin/gimp-2.8"}],"extensions":["tif","tiff"]},"application/x-xpinstall":{"action":2,"ask":true,"handlers":[{"name":"Thunderbird Mail","path":"/usr/bin/thunderbird"}],"extensions":["xpi"]},"image/png":{"action":2,"ask":true,"handlers":[{"name":"Okular","path":"/usr/bin/okular"}],"extensions":["png"]},"application/rtf":{"action":4,"ask":true,"extensions":["rtf"]},"application/vnd.oasis.opendocument.text":{"action":4,"ask":true,"extensions":["odt"]},"text/plain":{"action":2,"ask":true,"extensions":["txt","asc","text","pot","brf","srt"],"handlers":[{"name":"Kate","path":"/usr/bin/kate"}]},"application/vnd.ms-word.document.macroenabled.12":{"action":4,"ask":true,"extensions":["docm"]},"application/vnd.oasis.opendocument.spreadsheet":{"action":4,"ask":true,"extensions":["ods"]},"image/*":{"action":0,"ask":true,"handlers":[{"name":"gwenview","path":"/usr/bin/gwenview"}],"extensions":["jpg","jpeg","jpe"]},"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet":{"action":4,"ask":true,"extensions":["xlsx"]},"application/vnd.openxmlformats-officedocument.presentationml.presentation":{"action":4,"ask":true,"extensions":["pptx"]}},"schemes":{"http":{"action":4,"handlers":[{"name":"Firefox Web Browser","command":"env %u"},{"name":"thunderbird","path":"/usr/bin/thunderbird"}]},"https":{"action":2,"handlers":[{"name":"Firefox Web Browser","command":"env BAMF_DESKTOP_FILE_HINT=/var/lib/snapd/desktop/applications/firefox_firefox.desktop /snap/bin/firefox %u"}]}}}

That's weird indeed. Can you try the following?

 1. Close thunderbird, ensure it's not running any longer
 2. Hand-edit that file (/home/tony/.thunderbird/mmhujxko.default/handlers.json) to change the value of the action for the https scheme from 2 to 4
 3. Launch thunderbird and verify whether https links now open as expected in your default browser

Changed 2 to 4 and left everything else unchanged. http and https links now open Firefox.

Changed my system default to Chromium and that opened as expected. Now reverted to Firefox.

Thank you for your help. Happy to provide anything if you think worthwhile investigating further.

Well, it would be good to understand how you ended up with such a configuration in the first place, but I'm not sure how we could find out. In any case, I'm glad that the problem is resolved for you, I suggest closing the bug report for now.

Please do not hesitate to file new bug reports for other issues.