A system for minimizing the time required to initiate and terminate an instant messaging session. An initial message in an instant messaging session is checked to determine whether it has any significant content. If the received initial message has insignificant content, then a non-intrusive notification is provided to the user, without changing the current focus in the user interface. A pre-composed response message may also be automatically transmitted to the initiating user, requesting that a more significant message be sent. When an initial message in an instant messaging session is received that is determined to have significant content, the user is promptly notified in a different manner, which may be intrusive such that the current focus of the user interface is changed to a new window or the like containing the newly initiated instant messaging session. Detection of instant messaging session termination by the local user triggers a period of special processing of received instant messages from other participants in the terminated instant messaging session. Instant messages received from other participants in the terminated session during this time period that are insignificant farewell messages are processed without disturbing the local user.