Thunderbird 3 is having a problem with one of my IMAP accounts.

When sorted by date, it displays 10-15 messages at the top (newest) when in fact they are very old message. (pre-2010, over a year old, some up to 6-7 years old)

It's not game-breaking, but it is annoying, as I have to look past those to check for "new" messages. Is there any way to fix this? I'd considered re-downloading all the messages via IMAP, but that would take weeks (>50,000 messages).

When I open it, it displays the correct date, also when I use "View Source" the Date: header has the correct date (2009, 2006, etc). Is there any way to make Thunderbird realize that it should be sorted down with the rest of the 2006/2009 messages?

None of my other IMAP accounts (many with the same host server) have this issue.