SpamCop FAQ : Help for abuse-desks and administrators : Robots: Mailing lists and autoresponders :
Often, people who report spam say they did it because they found it difficult or impossible to unsubscribe through the regular channels. Also, many spammers use unsubscribe forms as a way to collect real addresses to add to their lists, so users are wary of giving their email address to unknown (or forgotten) web-sites.

Easy, anonymous unsubscribe

One way to handle this is to provide an easy and anonymous unsubscribe link in your outgoing email. Assign each user an id number that differs from his or her email address, and keep some sort of database (even if it's just a spreadsheet) of these userids. Then create a link in your mailings that automatically unsubscribes people based on ID, like this:

http://www.mylist.com/unsubscribe?userid=1234

Now, users just have to click once on the link, and they are unsubscribed without having to reveal their email addresses.

This technique is also very handy when you are faced with a spam report. Every spam report includes a copy of the spam, so you can just click the link, and know that the person has been unsubscribed without having to grep through logs files.
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