Messaging spam, sometimes called SPIM, is a type of spam targeting users of instant messaging services.
The increase in messaging spam may be motivated by its rise in popularity as well as the many steps to crack down on spamming since the late 1990s.

Using privacy options to guard against messaging spam
The free AOL Instant Messenger (AIM) service allows users to 'warn' other users. The warning decreases the number of messages an account can send, slowing down spam, and shows the AIM address as warned to other users that it may try to message. This feature does have the potential for abuse, although such cases are minimal.