Solved sm-msp-queue

Every half hour I get the following msg on the console:-

Mar  2 08:36:26 Server4 sm-msp-queue[9866]:  v21501Sn003234: SYSERR(root): timeout writing message to []

Can anyone tell me what that means and how I can stop it? I assume it has something to do with SENDMAIL...
Looks like something that's stuck in the queue. What does mailq show?
(host map: lookup (Desktop): deferred) <root@Desktop>

Desktop is the hostname on this computer. I guess this delving into Sendmail somewhere...