Tracking Mail Flow " user cannot get mail from server"

Please help to tracking message from mail flow on ECP.   Why user cannot get mail  ?

Delivery Report for User1@test.in.th
Pending
3/19/2014 9:36 AM exchmb01.test.in.th
The message has been transferred from exchmb01.test.in.th toexchmb02.test.in.th

3/19/2014 10:33 AM exchmb01.test.in.th
No further information is available about this message because the logs are no longer available.