I have a mail stuck in the exim mailqueue

The message log indicates the following

2009-06-11 06:31:22 1MESvC-0004YQ-Nz == *******@********.co.uk R=lookuphost T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<********@**********.co.uk>: host mailfoundry.easy-internet.biz [206.212.240.122]: 450 Domain in Reverse-Path resolves to an invalid IP address

Grepping the log for the message id reveals...

2009-06-10 18:53:15 1MESvC-0004YQ-Nz <= mailman-bounces@clone.cpanel.net H=localhost (server.domain.com) [127.0.0.1] P=esmtp S=3619 id=mailman.8.1244659986.22238.list_domain.com@domain.com T="Admins post from User@domain.com requires approval"
2009-06-10 18:53:15 cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1MESvC-0004YQ-Nz
2009-06-10 18:53:22 1MESvC-0004YQ-Nz == ********@*********.co.uk R=lookuphost T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<*********@********.co.uk>: host mailfoundry.easy-internet.biz [206.212.240.122]: 450 Domain in Reverse-Path resolves to an invalid IP address
2009-06-10 18:56:06 1MESvC-0004YQ-Nz == *********@*********.co.uk routing defer (-51): retry time not reached

The hostname resolves to the correct ip address and the rdns for the ip equates to the hostname, so there's no problem with other mails, it just seems to be the mailman transport when using exim is passing the 127.0.0.1, which obviously is a non-routable address.

Anyone got any ideas on where might be best to start looking