In response to detecting an incoming message (such as an email message, a text message, or a voice message) sent by a sender to a recipient, a computer system determines whether a current context of the recipient satisfies a condition. If the current context of the recipient satisfies the condition, then the system selects a response message based on the current context and sends the response message to the sender. The system's decision about whether to respond automatically to subsequent messages sent to the recipient may vary as the recipient's context changes. Furthermore, the system may select and send different response messages based on changes in the recipient's context.