The techniques disclosed herein provide systems that provides delegation for unavailable participants that are mentioned in a communication session, such as a channel, chat session, email thread, meeting chat, etc. When a system detects that a person, also referred to herein as a “primary participant,” is mentioned in a message, e.g., an “@mention” or “@name” is detected, and the system detects that the mentioned person has set an out-of-office reply or otherwise indicated an unavailable status, the system automatically identifies a delegate and packages the immediate message including “@name” and the message thread including the immediate message, and sends the packaged communications to the delegate. Permissions are also modified so that a computer associated with the delegate can display messages of the thread and send messages to the thread on behalf of mentioned person. When the delegate responds, the system directs the response to reply to the main thread.