By doing that, you're teaching your mail client and, if your mail is hosted by Google, Gmail that that message was unsolicited and should not have been delivere

By doing that, you're teaching your mail client and, if your mail is hosted by Google, Gmail that that message was unsolicited and should not have been delivered to you or anyone else. That's bad! The solution is to set up filters to send messages you don't care about to non-inbox folders.