I was doing some changes to the server (writing an Transport Agent). After trying to install it, I started to get some errors.
Now, when connecting to the SMTP server the session hangs just after finishing the DATA section. I'm not sure what happened, I disabled my transport agent and uninstalled it, then restarted the server. The problem persists.
In the Event Viewer, four of the same errors show up:
Source: FSCTransportScanner Category: Scan Error Event ID: 5021 Description: Unable to retrieve internet monitor interface.
What could have happened?