[Exim] help!

Hi guys, I am trying to pipe all emails to user@??? to a script which
should autorespond and then forward the mail to me in a new format. While
the script should work fine, exim seems to freeze the emails everytime
saying:

2001-02-25 14:23:39 14X9Zr-0007rH-00 == sites@???
R=lookuphost defer (-1): remote host address is the local host
2001-02-25 14:23:39 14X9Zr-0007rH-00 Frozen

Any ideas why this is doing this would be appreciated

thanks

William