What do you mean that it has stopped displaying messages? The folder seems empty? You see headers but no bodies? No new messages are being saved in the sent folder?

The sent folder displays emails sent from 11 Mar 2025 (that's around the date that I installed Thunderbird, having ditched Outlook) to 4 June 2025, and then 5 today. These 5 were sent from my phone. There is no "number total" of these shown (like there is for Inbox). Emails sent from my Android phone do get displayed (same email address), but emails sent from Thunderbird do not.

Check account settings > copies & folders for where your sent messages are set to be saved.

I've done that. Place a copy is checked, and the sent folder is correct for my usual email address.

Is everything else working as expected?

Is an error message produced after sending messages from Thunderbird?

Is this a Microsoft account?

Thank you very much for your help Scooter! Yes - everything else seems to be working normally as far as I can see. No – there are no error message when I send emails from Thunderbird. They do appear in the Sent Folder ok. I’m not sure why you are asking about Microsoft accounts. My email address cj69again@gmail.com is the normal address that I’m using¸ and it’s a joint address with my wife Jennifer. We’ve been using this address for several years, so it’s not new. I login to my Windows 11 HP laptop with an @outlook.com email address, plus a PIN as I have done for several years, and indeed this a Microsoft account. I can of course open this account directly. The cj69again@gmail.com is a “recovery” feature for the @outlook.com Microsoft account, so not sure if that’s a factor for my Thunderbird issue.

I stopped using Outlook on my PC (fully purchased product not the 365) as I got fed up with the New versus the Classic functionality. I do still use Outlook on my Android phone however. Today some of my “TEST emails” sent from the phone do clock up ok in the Thunderbird sent folder, but some don’t. Should be the same on both surely.

My sent folder has stopped displaying the sent emails.

No – there are no error message when I send emails from Thunderbird. They do appear in the Sent Folder ok.

How should one understand these two apprarently contradictory statements?

From another thread (would you please keep comments in the same thread?):

To Scooter. The statements were on different days/times. I can live with this. I think when there were several emails sent from my phone, it was quite a long time on that occasion until they eventually did display in the Thunderbird sent folder. I think I will now review my home sync, and WiFi details etc, so I will shortly close my query. Just before I do this closure, it would be helpful to understand why you asked "if it was a Microsoft account" to which I said "no it's a Gmail address" - is that a possible factor in all of this?

If you are using your Gmail account everywhere, then my inquiry is not relevant. But Gmail could have some quirks that I don't know about because I do not use Gmail.

In any case, I asked about a Microsoft account because I imagined that Microsoft's use of folders for sent messages that are different from sent folders on IMAP accounts could cause your symptoms. When I had a Microsoft account that I accessed from two e-mail clients on my computer and one on my phone, it was easy to end up with copies of sent messages in zero folders or two folders. Some trials and errors were needed to get all sent messages saved in one folder. One has to be careful about the options in account settings > copies & folders. Sent messages could also be saved in a folder that you are not seeing because you didn't know about it and did not subscribe to it.

If your problem is not really solved after the review that plan to do, please start a new thread and post all the information that might be helpful to other problem-solvers on the forum.

Good luck.