Sendmail (Deferred: Operation timed out...)

[Nicholas Henry]

FreeBSD 5.3-RELEASE (GENERIC) #0: Fri Nov  5 04:19:18 UTC 2004
 
Hello folks:
 
I'm trying to use sendmail to run a mailing list (a legitimate one!)
from a home computer behind a Linksys router using a cable modem. When
sending messages out they are left in the mqueue directory. Examining
the contents for files I find this error:
 
Deferred: Operation timed out with mx3.megamailservers.com.
 
I am a newbie to FreeBSD/Unix, so if there is some more information I
can provide to help me please ask. Any help would be much appreciated.
 
Cheers,
Nicholas