To amplify:

> 1) It's still in the queue.  If so, it should have a reason why attached to it.

Specifically, you can use the following LSCP.EXE command to see if the
message is still in the queue:

LSCP SHOW QUEUE /DESTINATION=BADDOMAIN.COM

where BADDOMAIN.COM is the destination domain of the message that didn't
get delivered.  If the message is still in the queue, you'll see it.  Then
you can do a:

LSCP RESOLVE/CONNECT BADDOMAIN.COM

to find out if that domain is receiving connections.

> 2) It has bounced, and you missed the bounce message.  If so, the LSMTP logs
> should say what happened.

Not actually by default.  For the most part, LSMTP only logs what you tell
it to.  If you're having trouble with mail to a specific domain, you
should enable site-specific logging for that domain.  See the LSMTP FAQ:

http://www.lsoft.com/manuals/lsmtp-faq.stm#2.6

The default logging for LSMTP (unlike sendmail) is very sparse.

> 3) It has been handed off to another mailserver.  In this case, contact the
> manager of THAT mailserver, and start over with this same list of 3 things.

If you've enabled site-specific logging per the above FAQ, and LSMTP shows
a successful delivery in the log, then it's out of your hands, and the
admin of the remote server needs to take over.

Another (very remote) possibility is that you've tinkered with the default
message expiration time, and set it to something shorter than the time
that it takes to actually deliver the entire mailing.  But if you've done
that, then you probably know how to undo it :)

--
Liam