A system that responds to a user setting a follow-up flag on a message within a first communication application by associating the flagged message with another user, such that the flagged message is available to a second communication application. When a user sets a flag on an electronic mail message contained in an electronic mail mailbox provided by an electronic mail application, the system responds by associating the flagged message with another user in a list of other users with whom flagged messages are associated. When a communication session occurs with the other user through another communication application, the system checks the list and determines that a flagged message is associated with the other user. The flagged message is then brought to the attention of the local user, for example within a list of flagged messages associated with the other user displayed simultaneously with the instant messaging session.