Running Zimbra 8.06.
Received emails show the proper date:
correctdate.png - March 31, 2014, 10:31

Then when I try to print the email the date changes to Wed, Dec 31, 1969 05:00 PM.
wrongdate.png

This happens randomly - sometimes from in house mail from the same server. This suggest to me the header has the correct time format.

Printing these emails is an integral business process for documenting the date it was received.