The following figure shows backboning between a Microsoft Exchange Server organization and a foreign recipient using a MAPI-aware client application. MAPI providers should be able to handle Microsoft Exchange Server rich text format.
Backboning to a foreign MAPI-based recipient
In this scenario, recipients using MAPI client applications are represented as custom recipient objects in the Microsoft Exchange Server directory. MAPI-based recipients are distinguished from native foreign system recipients by a Boolean attribute on the directory object. This attribute (PR_SEND_RICH_INFO) can be set by the Microsoft Exchange Server Administrator program.