I am having the same issue.
A few months back I upgraded my home G4 to Tiger from Panther (because I like to stay current)
Was thrilled with the upgrade overall, but in Mail, I noticed my work email was time stamped 5 hours ahead. Didn't think much of it because I only have my work email at home for occasional convenience. My home email (dotMac) is normal.
Last week, I finally convinced IT to let me upgrade my work computer to Tiger - they were a bit nervous to leave Panther behind.
So now I'm noticing that my work email here is ALSO stamped 5 hours off (my dotMac is still fine.) Only here at work, it is a bit more of a problem to have my email time stamped wrong.
I checked the mail preferences, I had IT check the server settings at work, on my work email, I can't find the problem. I am in Eastern zone, so GMT -0500, I suppose it's possible that Mail has somehow defaulted to GMT 0. But I can't imagine why. And why in Tiger but not Panther? And where else can I change the date other than in system preferences?
Here is an earlier thread on the topic which seems to establish that Mail is failing to subtract the given time from the GMT/UTC stamp in the email headers for a POP account.
http://discussions.apple.com/thread.jspa?messageID=6003127�
But no solution was found.
Any thoughts?