However, it also hosts sites such as Peacefire.org, which alerted members this week that Hotmail users have been unable to reach it for five months. After Peacefire protested, mail to the organization was allowed to continue earlier this week. Other companies besides Hotmail also may be blocking outgoing mail, but because they don't always notify customers, it's difficult to determine whether it's happening unless someone complains. When a company signs onto MAPS, it has several options to control spam. Or it can choose another, more sweeping approach that blocks e-mail, both incoming and outgoing, at the network borders.
Companies also can tailor their systems to block only certain sites or just incoming mail.
Hotmail apparently chose the most restrictive method. Kelly Thompson, MAPS' RBL project manager, said most companies choose the least severe technique. The idea behind blocking outgoing mail is to ensure that people don't reply to spammers, who often offer recipients a fake option of unsubscribing from their list. Instead of removing people, spammers use the incoming messages as a signal that an e-mail address is an active one where they can send more spam. He said he could understand blocking incoming mail, but the move to block outgoing mail disturbed him.