If you need to send your organization’s mail messages to two or more inboxes on different servers, set up dual delivery. With dual delivery, messages are delivered to a Enterprise email inbox, and to a non-enterprise inbox, such as Microsoft Exchange or an archiving server.
How dual delivery works
With dual delivery, incoming mail is delivered to a primary mail server first. The primary server delivers each message to the inboxes associated with it, then forwards all messages to a secondary mail server. The secondary server delivers the messages to the secondary server inboxes.
The primary server is the mail server identified in the MX records for your public domain.
Tip: The primary server can be either Enterprise Email or your legacy mail server. We typically recommend using Enterprise Email as the primary server However, you might use your legacy server as primary during a pilot or migration to Enterprise Email. When the pilot is over and you’re ready to switch everyone to Enterprise Email, update your mail to deliver only to Enterprise Email.