Techniques are disclosed for improving management of user information in instant messaging systems. Expiration criteria are defined, whereby one or more users or user groups may be considered as having “expired” from consideration by instant messaging functions such as presence determination. In particular, instant messaging activity is preferably used as an expiration criterion. Absence of inbound or outbound messages for a specified amount of time (or since a particular date/time) can therefore be used as a trigger for treating a user or group of users as expired. As a result, efficiency of an instant messaging system is improved by omitting the expired users and groups from subsequent management operations. Optionally, an expired user or group may be revived upon occurrence of certain events (such as a newly-arriving instant message from, or a change in presence status of, the user or group). “On-demand” expiration and revival are preferably provided as well.