This happens sometimes in IMAP accounts for an unknown reason. At least I don' t know the reason but it happened a few times with one of my IMAP accounts. When sending an email TB may show a warning box that your message had been sent but couldn't be saved in your account's "Sent" folder. In the same warning TB informs you that the message can be saved in Local Folders if it is OK for you. If you accept TB will create a folder such as "Sent messages_mapenzi@ free.fr" in Local Folders. So you will still be able to consult your sent message(s) in this particular folder in Local Folders.... I advise you to have a look in your Local Folders to find the particular folder containing those sent messages which could not be saved in the account SENT folder.

Thanks for your reply but....

I found that T-Bird was recently updated and that happened about the same time my sent file got corrupted.

It had always kept my sent messages in chronological order but now, not only are many of the latest missing, everything is in random order.

There is nothing critical in this except for my confidence in T-Bird/Mozilla. I live on less than $16k annually and I have donated when I can to Mozilla and T-Bird. I hope you can get things back to the way they have been from the beginning.

Jerry

I found that T-Bird was recently updated and that happened about the same time my sent file got corrupted.

You didn't describe a corrupted Sent file!

It had always kept my sent messages in chronological order but now, not only are many of the latest missing, everything is in random order.

First of all R-click on Sent folder > Properties > Repair folder.... Also you may have unintentionally changed the "View" of your Sent folder messages in the thread pane. To verify go menu View > Sort by.... (see picture) and View > Messages ..(see picture)

I live on less than $16k annually and I have donated when I can to Mozilla and T-Bird. I hope you can get things back to the way they have been from the beginning.

We are voluntary helpers in this forum and no programmers. I don't know how things were for you way back from the beginning (in Thunderbird ). Was it Thunderbird version 1.0 in 2004 for you ? For a better description of what the thread pane view of a Sent folder had been or should be you may show us an anonymised screen shot of another of your Sent folders (or even an Inbox), so we might be able to do a more precise diagnostic of your problem and find a remedy.

Thanks for your help. I guess my description of what happened to my sent file isn't considered corruption. On your suggestion I did, now, go to the 'view' and reset things the way they had been. If, or when, it happens again, I'll be better prepared in my efforts to fix things.

Thunderbird is one of - if not the most customisable - email clients "on the market". That's why I have never been able to switch to the frugal Apple Mail mail client (besides the fact that I already had been using Mozilla's ancestor Netscape Communicator in the last century). Maybe TB is too much customisable that users can easily get lost between so many menu bar/ toolbar entries and other settings. May I consider your problem as solved or do you still need help? I cant' see any of my replies marked as helpful...