[SpamCop-List] I'm blacklisted - no troubleshooting information available!

[John Wilson]

We're suddenly blacklisted, and spamcop won't give me any good information 
to troubleshoot with.  All it shows is 3 links basically saying "It could be 
anything - you're on your own".

We're running up-to-date virus/spyware scanners on every machine in the 
network, including the exchange server, and none of them are reporting 
infections.  The exchange server has blocked a lot of attachments tho. 
There are no autoresponders set up and the server doesn't allow relaying. 
At this point I have no idea what to look for.  Is there any way to get 
useful information about what exactly triggered the blacklisting?