An electronic mail (e-mail) application program includes a configurable, e-mail messaging feature for automatically responding to a portable computer's transition between online and offline states. The e-mail application program determines the state of a connection between a portable computer and an electronic mail server and processes electronic messages in accordance with the appropriate state. The portable computer's transition between an online state and an offline state triggers a user-configurable response, designed to permit the continuation of electronic mail message processing in a manner that accommodates the state change. The e-mail application program responds to such a transition by automatically switching between online and offline modes of operation. The e-mail application program can also respond to such a transition by establishing a secondary connection to a mail server when a primary connection is rendered inoperative. A user may configure various aspects of the invention to respond to a transition in a way that accommodates the user's hardware and/or software requirements.