Random emails not received

Random emails not received

I can't seem to figure out what is going on with my email.  I seem to be getting messages but twice now I was expecting a message that never came.  When I contact the sender they tell me it was sent and no errors were received.  I have them send the message to an alternate address (yahoo) and it goes through fine.  Both of these were related to jobs so I am concerned that I am missing others and don't know about them.  Any help would be appreciated.

Josh