Newsletters are used to advertise websites products and services, these days they are mainly delivered via email service, but after some period of time it may become boring, annoying or simply we will not need those leaflets anymore. In such situation we have to unsubscribe newsletter in order to stop receiving them. People have to have this opportunity to unsubscribe newsletter that is being send. When you request for leaflets you may be in risk of getting a spam messages. Spam is a form of bulk email the main difference is that spam are not requested commercial messages, unlike normal mass emails and they are not legal anybody receiving unsubscribed newsletter can report the sender of it as a spammer. The email address will be added to a black list of your filter this action will not let through any messages that are send from this address. When you decide to unsubscribe, newsletter may still be available to receive in order to do that you have to subscribe again.