Define delivery routes
Use the Delivery Route page under to define the domains for which email traffic will be routed to and from the email hybrid service, and the SMTP server addresses that receive mail from and send mail to the hybrid service. Each group of one or more domains and one or more SMTP server addresses comprises a delivery route.
Important: Email hybrid service checks the connection to your SMTP server by sending commands to a “postmaster” address. If your SMTP server does not have a postmaster or administrator
address (for example, postmaster@mydomain.com) you should add it manually before completing this step.