Time stamp issue - Atlantic time

We have begun experiencing a strange issue and wonder if anyone else has seen / corrected the same…

In our domain there are 4 servers…the admin server where all internet mail routes in and out from is on mountain standard time. We have found that when an internet mail message comes in for or from a sender in Atlantic time zone the time is off by 3 hours.

An example : person A sends a message at 10 am Atlantic time, received on Notes server time showing is 10 am Mountain time…the message forwards to the person on our Atlantic server, time shown at delivery 1 pm. Normally one would think the message would send at 10 am AST, arrive on admin server 7 am MST, deliver to recipient 10 am AST.

We also have a server in Eastern time and no time stamp problems exist on messages delivering to or from there…

I am stumped…