Suddenly stopped receiving/sending mail. Can't figure out what the problem is. I have a log full of messages like the following..

from /var/log/exim_mainlog:
2004-09-26 22:17:27 1CBkVG-0002CP-1e == webmaster@missourirunning.com routing defer (-51): retry time not reached
2004-09-26 22:17:27 1CBjRp-0001Rr-Nr == chris@giftandforget.com routing defer (-51): retry time not reached
2004-09-26 22:17:26 1CBR5a-00013M-BU == chris@giftandforget.com routing defer (-51): retry time not reached
2004-09-26 22:17:25 1CB94E-0000iA-RE == charles@piratedeals.com routing defer (-51): retry time not reached
2004-09-26 22:17:26 1CBdNo-0006IZ-2G == amplitudecaitrin@lowerpricemeds.net R=defer_router defer (-1): All deliveries are handled by MailScanner
2004-09-26 22:17:22 1CBfxk-0007Hs-CB == info@mail.flashcash.com R=defer_router defer (-1): All deliveries are handled by MailScanner
2004-09-26 22:17:24 1CBJRO-0003Qz-9B == webmaster@missourirunning.com routing defer (-51): retry time not reached

from /var/spool/exim_incoming/msglog
2004-09-25 15:46:25 Received from service@tscgraphics.com H=(missourirunning.com) [24.207.184.114] P=esmtp S=41303
2004-09-25 16:01:09 webmaster@missourirunning.com routing defer (-51): retry time not reached
2004-09-26 15:49:15 webmaster@missourirunning.com R=defer_router defer (-1): All deliveries are handled by MailScanner

Where do I go from here? I'm using cPanel and running Exim 4.42.

You may want to contact your hosting provider and make them check into it

I've exactly the same issue. Started around 5 hours ago.

There is a definite move away from MailScanner support in newer cPanel updates.

I reverted back to a fresh copy of exim.conf and it seems to be working now. The only changes that had been made to it were resulting from MailScanner install. I'll probably investigate some other options in the near future.

It was mailscanner for us too :)

Don't know which MailScanner install you guys are working with but the following one has worked perfectly for us up to the current cpanel stable release.
http://www.webumake.com/free/mailscanner.htm

I installed it several months ago and it had been working fine until a couple nights ago. Still not sure what the problem really was.