Microsoft Exchange Transport Service may not start after Upgrading to Exchange 2013 SP1
Suppose you have exchange 2013 environment, and you installed SP1 and after that Microsoft Exchange Transport Service will not start and stay in Starting state. You followed KB 2938053 but it doesn't fix the issue.
This may relate to Relay receive connector configures on port 25 with Server Role as Hub Transport or there is a conflict on Bindings between HUBTransport and FrontendTransport Transport Role.
To confirm the above, Run command below from Exchange Management Shell
Get-ReceiveConnector | FL Identity, Name,bindings,Transportrole
More Info:
Port 25 – This port just like in previous versions of Exchange is used for SMTP. Used by both External SMTP into the Front End Transport Service (FET), SMTP with Exchange 2007\2010 hub servers, between MBX servers, and also from the FET to the Transport Service. There is a receive connector named Default Frontend <servername> that listens on this port.