Well, the ip address 127.0.0.1 is called localhost
, i.e. the system itself.
Comsat is the server process which receives reports of incoming mail and notifies users if they have requested this service. Comsat receives messages on a datagram port associated with the ``biff'' service specification (see services(5) and inetd(8)).
...so it seems like your machine is connecting the mail system for something. I'm not an expert, read about "in.comsat" the first time today, but to me that doesn't seem harmful (well, somebody wiser might want to talk about that).