Messenger service spam
In 2002, a number of spammers began using the Messenger Service in Microsoft's Windows NT-based operating systems to get their message across. This isn't the same as the Windows Messenger instant messenger application included with Windows XP; rather, it is a function of Windows designed to allow servers to send alerts to administrator workstations. Windows Messaging spam appears as normal dialog boxes containing the spammer's message. Windows Messaging spam can be delivered using any NetBIOS port, so to block it at a firewall entails closing down ports 135 through 139, and 445.
Alternatively, Windows users can simply disable the Messenger Service entirely though the Windows services list available via Run/services.msc.
Messenger service spam, in particular, has lent itself to spammer use in a particularly circular scheme. In many cases, messenger spammers send messages to vulnerable Windows machines consisting of text like: "Annoyed by these messages? Visit this site." The link leads to a Web site where, for a fee, users are told how to disable the Windows messenger service. Though the messenger service is easily disabled for free by the user, this scam works because it creates a perceived need and then offers an immediate solution. Often, the only "annoying messages" the user is receiving through the Messenger service are advertisements to disable the Messenger service itself.
Subsequent Windows XP Service Packs have disabled the Messenger Service by default.