Router stop delivering INBOUND SMTP messages

I have a strange problem with a server; It has suddenly stopped routing INBOUND SMTP messages! All outbound is working perfectly, but noone is receiving any messages. All mail is simply stuck in the mail.box without any errors anywhere; they do not become dead (or held), there is nothing in the log.nsf that indicates any problems and still, the router task is just idle.

Have anyone seen this behaviour before? What to do about it?

I’m not an administrator - just helping the admin when he is on vacation…

Subject: Finally, I found the problem; Directory Assistance was corrupt somehow…

I disabled the DA, restarted the server, enabled the DA back again and restarted the server and everything seems to be working now.