I was having the exact same issue. Whenever I tried to send a message, I got this output:
console.error: mailnews.send: ({}) console.error: mailnews.send: "Sending failed; , exitCode=2147500037, originalMsgURI=" For what it's worth: My Download directory is on an external SSD I was able to fix it using this command: snap connect thunderbird:removable-media -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to thunderbird in Ubuntu. https://bugs.launchpad.net/bugs/2065542 Title: Thunderbird snap unable to send or save messages with custom download dir location Status in thunderbird package in Ubuntu: Confirmed Bug description: Package: thunderbird Version: 2:1snap1-0ubuntu3 I have KDE with custom downloads folder location (/mnt/M.2/Downloads in my case), and when I try to send or save message I have msg box with "error sending message" In `journalctl -f` there is following message kernel: audit: type=1400 audit(1715558212.734:570): apparmor="DENIED" operation="mkdir" class="file" profile="snap.thunderbird.thunderbird" name="/mnt/M.2/Downloads/thunderbird.tmp/" pid=52900 comm="thunderbird-bin" requested_mask="c" denied_mask="c" fsuid=1000 ouid=1000 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/2065542/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp