Having problems with Exim: unrouteable mail domain

I noticed a problem recently with the email program not sending or recieving emails. I went into WHM and "Manage Mail Queue" and used the deliver now function. Here is the following response:

Message 1BwimE-0006FB-IC is no longer frozen
LOG: MAIN PANIC
failed to expand condition "${perl{checkusersa}{$local_part}{$received_protocol}}" for sa_localuser router: Undefined subroutine &main::checkusersa called.

LOG: MAIN PANIC
failed to expand condition "${perl{hasfilterfile}{$local_part}}" for central_user_filter router: Undefined subroutine &main::hasfilterfile called.

LOG: MAIN PANIC
failed to expand condition "${perl{checkvalias}{$domain}{$local_part}}" for has_alias_but_no_mailbox_discarded_to_prevent_loop router: Undefined subroutine &main::checkvalias called.

LOG: MAIN PANIC
failed to expand condition "${perl{checkspam}}" for lookuphost router: Undefined subroutine &main::checkspam called.

LOG: MAIN PANIC
failed to expand condition "${perl{checkspam}}" for literal router: Undefined subroutine &main::checkspam called.

LOG: MAIN
** go3team@comcast.net <xxxx@ironmaiden.mtahosting.net> R=fail_remote_domains: unrouteable mail domain "comcast.net"
LOG: MAIN
Frozen (delivery error message)


If I send a message to the server, I get a bounce back message with the following:

Reporting-MTA: dns; comcast.net
Arrival-Date: 16 Aug 2004 14:43:51 +0000

Final-Recipient: rfc822; <xxxx@mtahosting.com>
Action: failed
Status: 5.0.0 550-Verification_failed_for_<xxxx@comcast.net>
Diagnostic-Code: smtp; Permanent Failure: Other undefined Status
Last-Attempt-Date: Mon, 16 Aug 2004 14:44:03 -0000

A message (from <xxxx@comcast.net>) was received at 16 Aug 2004 14:43:51 +0000.

The following addresses had delivery problems:

<xxxx@mtahosting.com>
Permanent Failure: 550-Verification_failed_for_<xxxx@comcast.net>
Delivery last attempted at Mon, 16 Aug 2004 14:44:03 -0000

I've run out of ideas, I would appreciate some help. Thanks.