SpamCop FAQ : SpamCop Parsing and Reporting Service : Parsing and reporting spam with SpamCop - decisions, problems :
Although these addresses can sometimes contain valid contact info for a spammer, they are much, much more often just fakes. I have tried reporting them in the past. Doing this results in far too many spam reports to innocent administrators. If you are sure the reply-to is really valid, you can use host-tracker to find the administrator yourself and file a report manually. Unfortunately, if I make this too easy, people will do it without thinking.
[Append to This Answer]