Never use the webmaster address. Once it gets spammend, you're doomed to it. Any other address can be changed to get rid of spam.

I have two such E-mails from my webhost. I don't mind spam that much though. Sometimes, when in large quantities, I get amazed by it and snag screenshots like this from early September 2005 and this from early January of 2006. I have one other such screenshot, but I haven't posted it yet on my website. 100 spam messages per day in these extreme cases....

use instead a third party e-mail provider that allows you to automaticly route/forward the e-mails. the 3rd party host system then scans for purposly uploaded virus/trojens ( sometimes you get these from people that know you reported them, warez users tend to be a major source of such things)

they will sometimes Intentionaly register your e-mail to sites that genarate ALLOT of spam. ( you can then easily drop and create a new 3rd party e-mail address without upsetting your web host. using your web host e-mail for contact with such malitious users can cause so much traffic backlog for a host system over thier network and routers and virus detectiing ( which usualy increase traffic for the host due to automated messages kicked out ) that such a targeted web site they host can be temporarily suspended.

a web site i frequent often is currently down because of the above problem. too much malitious spam junk e-mail was directed to the contact e-mail address which was part of the guys account on that host site.
He is not sure when his host will allow his site back up, if at all.

Just leave them alone, don't answer their questions.
Why spend so much effort on warez users.

The best is recording his IP adress and email,
and send that with a screenshot (reduced size, not fullscreen)
where he confirms the warez using to Conitec.
But be carefull with warez assumptions, time is money
and I dont think Conitec wants to be filled up with mails
about possible warez users.

old_bill

I'm not going to tell you how to run your site, but I normally do the following:

Ban the user.
Get all the user's info (posts, IPs, PMs, etc.).
Send the user an email telling them why they have been banned (be professional about it).
Post on their threads a message explaining why it is stupid to use warez (its buggy, normally a Trojan Horse program, can get you into legal troubles, etc.).
Lock down their threads.

If you have time, follow up on the user's info you saved. See if he's done this before. Read his PMs (surprising what people will say in PMs). See if he has other contacts on your forum. Etc. You can waste a lot of time doing this, so save this for "special cases" or times when you want to test your tracking skills.

Don't worry too much about "hacker payback". Most of these warez users are not very smart (they wouldn't have been caught if they had half a brain ). So as long as your website isn't wide open to script-kiddie attacks they are not going to "fry your hard drive" or something silly like that.

Also, make sure that YOU don't do anything illegal. Reading their PMs is legal, using the information in it to hack their email account is illegal. Telling them that they are breaking the law is legal, but calling their mom can be considered harassment in some states (but it sure is fun ).