Speaking of email problems, I've had one too. Not like yours, but enough of a problem to make me start looking for other Tiger users with email issues so I can figure this out.
A couple of weeks ago I checked my mail and saw the visual notification that I had two messages in a mailbox that I'd created (that is, a sub-mailbox of my Inbox). But when I selected that mailbox, there were actually no messages there. Worse, the hundred-odd
other messages I'd received in that mailbox were no longer visible.
Prior to this (several months ago) I'd set up a Rule for sending specific messages to that mailbox. Don't know if this has anything to do with it, but there were about 15 senders assigned to this rule.
Now I'm seeing the same thing happening again, only to a different sub-mailbox. I see the notification that I have one message in that mailbox, yet when I select that mailbox, there's no message there.
What I wound up doing for the first one, just so I wouldn't actually lose the messages, is save the messages by going to [my user directory] > Library > Mail > Mailboxes >[the corrupted mailbox] > Messages, and backing up that folder to my external HD. Of course, the messages don't have their original titles so it's virtually impossible to know who sent what, but I figure if in a pinch I have to refer back to them, I have them.
Long story short, I'm wondering if this is a Tiger issue. I've had Tiger for some time now, and this is the first time this has happened, but hey, there's a first time for everything!
G5 dual, 23 Apple Cinema Display Mac OS X (10.4.2)