Transport Neutral Encoding Format

Transport Neutral Encoding Format (TNEF) provides a standard method for passing both textual and binary message data. In this method, TNEF encapsulates MAPI properties not supported by an underlying messaging system into a binary stream that can accompany a message through transports and gateways. The target transport can then decode the encapsulation to retrieve all the properties of the original message.

Because a message consists of MAPI properties, your gateway can use TNEF to encapsulate the message properties into a binary stream. This stream can then be attached to an outbound message for transfer by the gateway. A gateway must be able to determine whether an attachment is a TNEF attachment.

You can use TNEF when you want to create extra MAPI properties (for example, in a custom message class) and put these extra properties into an attachment. You can also attach multiple messages to each other in a form that the foreign system understands. Using TNEF lets you transmit messages with more complex formats, such as rich text.

When mapping addresses, first determine whether any of the Responsibility-TRUE recipients are TNEF. The Boolean MAPI property PR_SEND_RICH_INFO indicates whether the recipients can use TNEF. Send all TNEF recipients a separate message containing the TNEF attachment.

Note  Do not include reports in TNEF attachments.

TNEF attachments can be included in or excluded from the TNEF stream. Excluded attachments must have unique names. TNEF generates a tagged form of the message text that is used on inbound processing to recover attachment positions.

For detailed information about TNEF, see the MAPI Programmer’s Reference.