Just installed 2013 exchange server, we noticed after a couple of days that we did not receive any external emails throughout the night. I could not find anything wrong with receive connectors. Telnet works internally when this happens but NO access from public side testing with telnet. After I restart the Microsoft Exchange Transport service everything functions just fine and normally lasts for about 8 hours until it happens again.
I dont know what to check or look for at this point. Very new to exchange 2013, any kind of advice would be helpful at this time.