A gateway must translate the content of each message that passes through it into a form that can be understood by the system receiving the message. If the message contains an attachment, such as a document or spreadsheet, the gateway must also deliver the attachment.
The gateway can handle the message content in several ways, depending on the characteristics of the mail systems it serves. For example, Microsoft Exchange Server can generate rich text in its messages, but PROFS systems cannot properly display rich text. A gateway between these systems needs to convert the rich text into a binary stream that PROFS can use.
Microsoft Exchange Server gateways perform message content translation by using conversion DLLs. The Microsoft Exchange Server SDK provides conversion routines to handle some types of messages, such as those generated by Microsoft Schedule+. You can also write your own conversion routines for translating between Microsoft Exchange Server and other foreign systems.