Hi Gerrit

I was not able to successfully replicate the issue. I tried the below steps.

Tested on v13 and beta v14.03 with gmail imap connection.

1. Enabled phone's Aeroplane mode. (Network disabled) 2. Sent an email. (Send failure observed). 3. Moved the email from outbox to draft. 4. Checked sent folder. No email present. 5. Disabled phones's Aeroplane mode. (Network enabled) 6. Opened and sent the email in the draft folder. 7. Email sent successfully. 8. Checked sent folder. Only one copy of the email was present.

I also repeated the steps (skipping 1 & 5) with WAN access disabled on router.

For network outages you don't need to move the email away from the outbox. It will send when network connectivity resumes. I tested this also.

What was the reason your email failed to send? Did the error message specify? Are you been able to replicate both the send failure and email duplication in the sent mailbox?

Hello platform,

I tried to reproduce the issue with: - browser link to email address - android contacts app w/ email address

And thunderbird was behaving fine.

None the less: - other issues here report exact the same problem - my issue is no network outage as I am in reliable WiFi network

It just leaves the email in the outbox, gives the error and sends from Entwürfe the second time without error, but with two entries in sent folder.

I will think of a different way to reproduce the issue...

That does sound frustrating, Gerrit. Thanks for explaining the issue in detail — that really helps. It seems like a syncing problem with the outbox on Thunderbird mobile. You could try clearing the app’s cache or checking for the latest update; that often fixes similar issues. Hopefully, the developers can patch this soon so sending emails works smoothly again.