Right click the folder, select properties and then the repair button. What size is it on disk after compact.

Seems to have worked. About 2800 messages taking up 1.8 GB. Did the same thing on my Mail Read folder that is about 2-3 times that size. Got loads of really old messages that hadn't shown up before. So one thing is that missed messages will show up as today instead of when they were actually received (2013), but since I use the search function to look for old messages that's not an issue. This also explains why I have sometimes not been able to find old messages (sent or received) that I was pretty certain should have been there. It did take quite a bit of time (still running after 30 minutes on AMD quad core laptop with 4GB RAM.). But tested it with test messages to my other emails and they saved to sent folder quickly. Thanks much.

The presence of today's date in that listing is very concerning. Given that repair only rebuilds the index to the store. They should appear with their original dates. I strongly suspect there is data corruption there. Moving all mail to a new folder and compacting again is the only way to clear that out if it exists.

The repair should be quick, a minute at most. The compact involves reading and writing the 1.8 Gb to the disk but again. With modern disk drives it should be the work of only a couple of minutes, not half an hour. I strongly suspect your anti virus is trying to scan files while Thunderbird is using them resulting in exceedingly slow operation on all fronts. You need to look at excluding Thunderbird profile folder for any on access scanning.

Actually it's not antivirus scanning. Thunderbird is reloading the entire folder from the server. Which of course takes forever, especially if I'm on WiFi and 6 MBPS download ISP.

Any ideas why Tbird is reloading the entire folder from the server?

slpederson said

Any ideas why Tbird is reloading the entire folder from the server?

Yes

Thunderbird 24.2.0, haven't made any configuration changes in ages.

The bug was fixed in 34

The machine I'm working on now says it's running 31.4.0. Have automatic updates to the Release Channel on. This leaves me a bit confused. Are you suggesting I use a pre-release or beta version?

slpederson said

I have been having an increasing problem with over 50% of the time getting repeated "There was an error saving the message to Sent. Retry?". Eventually it works, but frequently takes as many as 6-8 tries. This happens on multiple machines running both Windows 7 and Windows 8.1. I use IMAP, and my email server has no size limits, I have unlimited email storage. Sometimes Thunderbird will show multiple copies in sent mail. I haven't checked with recipients to see if they are receiving multiple copies but no one has said anything to me. Thunderbird 24.2.0, haven't made any configuration changes in ages. Error started about 4 months or so ago and keeps getting worse.

I am running Vista Business. This problem appeared all of a sudden. The Sent folder stopped displaying its contents. I looked up this bulletin board for ideas on how to fix it. First I tried to Repair the Sent Folder in Properties. It wouldn't let me; said something like "The Folder is in use by another process". However, I was successful in Compacting the folder, and that has restored the contents of the Sent Folder.