For some weeks I observed a strange behavior in Thunderbird on one of my IMAP accounts:
- read messages where marked unread again, after each sync with the server
- flagging messages resulted in the wrong message flagged
Since I didn’t have any problems with that account at home, where I use Apple Mail to get my mails, I suspected an obscure bug in Thunderbird. Subsequent queries on the net to find references to this behavior weren’t successfull.
After installing Tiger on my Mac and launching the new version of Apple Mail I was forced to investigate the issue in more detail: Tiger’s Apple Mail hung on syncing the account in question, not displaying a single message. All other IMAP account were working just fine.
So I had to look more carefully at the server. After some copying around of message files in the maildir folders, checking the account via Webmail (SqWebmail), I was finally able to find the culprit: in the Inbox folder was one message, which was owned by root instead of the user of the mail daemon. Obviously the mail daemon had no access to that file. Changing the owner solved all issues in Thunderbird as well as in Apple Mail.
Bottomline: I don’t remember when I why I copied that file with the root user in that directory, interesting though that the different mail client were reacting in such different ways, making it somewhat difficult to figure out where the problem might be.