The most popular instant messaging programs see over one billion messages a day. Like e-mail, IM comes with its own security problems. Most free IM programs, such as AOL's Instant Messenger and Yahoo! Messenger, are set up by individual users, not IT staff. That means no uniformity or central control. User names, for instance, don't need to match your company's e-mail addresses, which makes authentication tough. And IM is susceptible to viruses and junk messages (known as spim).

E-mail software makers are beginning to offer their own instant messengers, but these often don't play nice with other IM programs. Companies that want to use IM may be better served by IMLogic's IM Manager (starts at $25 per user), which offers content, spim, and virus security, as well as content filtering for regulatory compliance and archiving. Other vendors, including FaceTime and Akonix, offer similar products.