User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.0 (KHTML, like Gecko) Chrome/3.0.195.38 Safari/532.0 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091204 Thunderbird/3.0 With auto-compacting on, the inbox is sometimes compacted when messages are removed from it. When this happens, the next message is not automatically selected - you have to click on the next message for it to be previewed. Reproducible: Sometimes Steps to Reproduce: 1. Turn on the option to compact folders when it will save (a low number) of KB. 2. Have lots of messages in your inbox. 3. Delete them one at a time. Actual Results: Sometimes, the next message will not appear after you delete one. It only started happening after I turned on auto-compacting, but I can't reproduce it on demand. Expected Results: Should always go to the next message. This behavior occurs in Thunderbird 3 on both Windows XP and Windows 7.

When this happens, are there error messages in Tools -> Error console ?

(In reply to comment #1) > When this happens, are there error messages in Tools -> Error console ? No, it doesn't seem to write to the error console.

I've tried to figure out how to make it more recreatable, and it looks like Thunderbird only compacts and indexes messages every once in awhile, but specifically when you first start it. If you have a lot of large messages in the Inbox, and a lot of large messages waiting to be downloaded from the server, while it's doing Send/Receive the very first time after starting the app, if you start deleting messages, you should see the behavior. It seems to happen when Thunderbird is indexing messages, which looks like it's happening at the same time as compacting.

For me the problem reproduces. Messages from a certain mailing-list are automatically (by a filter) sent to a specific folder (> 1MB in size). After the _first_ delete of a new message (or multiple new messages) in that folder, no other message is selected. If I delete any messages after that, the next message is selected as usual. Note that all messages in that folder are small (most <10kB, largest about 40kB). The problem occurs when I delete the first message(s) after the Send/Receive has finished. This happens when "compact folders when..." is set to 50kB. If I disable the filter so that the messages go to my Inbox (which contains just a few smaller messages) instead of the large folder, the problem does not occur.

Reporter, do you still see this problem when using a current version of thunderbird? And if you do not, please close bug report by changing resolution to worksforme

I've actually switched to a different mail client since then, so I don't know about the current version. So if you cannot reproduce it, you're welcome to close out the bug.

I cannot reproduce the problem with version 9.0.1.

This issue has been happening with me for several years now. I never equated it to auto-compacting until I found this bug report. Steps to reproduce: 1. Start Thunderbird and download new massages. (Downloading new messages may not be necessary but this is the procedure I've always followed) 2. Select any message in a list of messages in any folder. (I've always selected an unread message but, again, this may not be necessary) 3. Delete the selected message. Result: About 60-70% of the time, all messages get unselected (The next message fails to auto-select so the message pane is empty). A message must be manually selected to display its contents. Once another message has been selected, everything functions properly, Additional messages can be deleted and the next one will auto-select. There are no repetitions of the problem. Restart Thunderbird and there will be roughly a 60-70% chance that the problem will occur for the first message selected in a list. This issue occurs across all application updates (many of them over the years), all OS updates (also many), and all hardware updates (an iMac Pro, the Mac Mini from 2014, and the Mac Mini just released in 2018). I've always had the auto-compact value set to 1 MB. Armed with this new information, I've changed the value to 5 MB and will experiment with other values or turn the feature off if necessary.