I have Droid 2 Global from Verizon, the email issue really drives me nuts. The factory email sync would stop and go randomly and I finally got fed up and installed Improved Mail. It worked for a while but it stopped since Nov. 27. I had to reboot it to make it work again.
The Gmail app just simply doesn't sync at all.
During this time period, I did not travel at all. I have both Exchange mail, Gmail and Yahoo Mail.