Sendmail is one of the grumpiest daemons around. The configuration file for it alone is nearly a programming language in itself. Its fun.
Anyway, if you're not running a mail server, I highly recommend killing the service.
If you are, and want to debug it, page through the entries in /var/log/messages and sendmail should be spamming that log with whatever is making it have a lengthly time-out like that.