Well, you could initiate a search in the trash folder if there are many messages there. Filters are a strong tool in Thunderbird and I encourage you to become familiar with them.

Thanks, David. I have been trying to use filters.

Some things were unclear to me. I ran a "move" filter on a large folder using the "Run Now" button. I clicked "Run Now," but nothing (apparently) happened, so I clicked again. Then later the filter log said it had moved a number of messages. But when I looked, they were still in the original folder. And still later there were multiple copies of the messages in the destination folder.

Then I didn't realize that "contains" matches substrings, not just whole words. I applied a short string to message bodies and got a lot of unwanted matches. So now I'm being cautious about that, and using short strings only in header fields.

So I'd have some tips about filters for newbies like myself:

1. The filter term "contains" matches all substrings, not just whole words.
2. Until you're confident about filters, test them for a while with "Copy" to a test folder instead of "Move". Later you can change it to "Move" and run it for keeps.
3. If you click something and there's no response, don't assume nothing happened. There isn't always an indication, or it might be subtle. And it might still be happening in the background.

Another example of this last: I accidentally deleted an email, hit ctrl-Z hoping to get it back, and nothing happened. (That was my original question.) But actually it was restored, it just didn't show in the folder until I went to another folder and came back.

I hope this doesn't sound too much like a gripe session. A number of ex-Agent users recommended Thunderbird, and I'm still on the learning curve. But I have fallen into a few traps and am hoping to help others avoid them.

Another newbie question: Is there a log file for server errors? They pop up for a few seconds and disappear.