Split domain implementations, while not recommended*, can address very specific client needs for a hosted enviornment. They can be used for the simulataneous hosting of basic and exchange email, hosted exchange accounts in conjunction with an internal or third party mail server, or a phased migration to exchange hosted services. Please reference the respective sections within this article for setup instructions.

*Routing email through the basic mail server bypasses the Exchange mail server's Spam filters, and may result in increased Spam.