In Phase II of the implementation, the Sender Mail Client should record the new Authentication Key Delivery. The mail client should put the Authentication Key of every outgoing message in the header.

This process should be transparent to the end user, and it should not require the user to know or enter the key; furthermore, when a new message is read with X-New-Auth-Key, it should not show the message to the end user.

The Mail Client needs to verify that the sender of the new Key is the Authentication Server of its domain.