This one time, at band camp, Scott Mohnkern said:
Well, I've almost got everything running after a system crash.
Pop is working now
However, sendmail will only take connections if you telnet to localhost
or 127.0.0.1, if you use the ip address, or the hostname, it refuses the
connection.
I don't have the firewall in place, so it can't be that,
and, i've put the domain name and host name in the local tables for
sendmail.
I assume that sendmail is only listening on localhost. Use netstat to
confirm. If this is the case, you'll need to instruct sendmail to
listen on the IP addresses you would like it to listen on.