list washing
In the language of spam, list washing is the process of removing an e-mail address from a mailing list when the recipient either requests removal or complains to the sender's ISP (Internet service provider) that he is being spammed. In the view of spammers, and some ISPs, list washing yields a "clean" list of e-mail recipients who don't object to receiving unsolicited e-mail.
In opt-in e-mail, when a mailing list is updated after a recipient opts-out, it's called data scrubbing .