Describes the Mercury system, whereby a user of an electronic message service receives messages on a device and in a format appropriate to his context (travelling, in a meeting, etc.); and ConChat, whereby besides transmitting his message he automatically transmits contextual information such as his location, the number and identities of other people in the room, the room's ambient temperature, lighting, and sound, other applications and devices running in the room, his mood, his personal status (on the 'phone, out to lunch, etc), and any activity in the room.