This sounds like the same issue as Bug 4033 and Bug 4909. In those cases, a message in the message cache has an invalid conversation ID for some reason -- even though the on-disk version of the message is fine.
We think this is some kind of a race condition either with IMAP or with the MAPI connector (Network Edition only) --- can you tell me if the affected account was using either of these? How about POP3?
Since the conversation ID is only corrupted in the in-memory cache, you can fix the account by forcing the cache to reload: the message cache is a max of 500 messages (per account) and so paging through other folders will do it...alternatively, as a last resort bouncing your server should also fix the problem. |