XFOR: Non-TNEF Attachments Inbound From IMC at Top of Message

Attachments to MIME encoded mail messages that arrive to a Microsoft Exchange recipient from the Microsoft Exchange Internet Mail Connector (IMC) might appear at the top of the message body. This can occur for any message originating from a non-MAPI compliant email client.

MIME RFCs 1521 and 1522 do not include a recommendation for representing where or how attachments will be presented to the user within client user interfaces (email client software). This decision is left to the discretion of the client software developer.

The experimental RFC1826 advances an enhancement to MIME that includes, among other things, the ability to position attachments or representations of attachments (tokens, icons, pointers, and so forth) in a particular location within the message body.

Microsoft's current implementation:

When receiving non-MAPI client originated messages with attachments, the Microsoft Mail 3.x Windows client and Microsoft Exchange client present all attachments as icons at the top of the mail message, with the most recent attachment first and, in the case of a multiply forwarded message [with forwarders adding additional attachments], subsequent attachments following chronologically.

Sending messages from MAPI compliant email clients to MAPI clients can exploit proprietary methods (TNEF) that enable the attachment to be presented as an icon within the message body, positioned wherever the sender desires. This is the default action for handling attachments when composing messages with the Microsoft Mail or Microsoft Exchange clients.

This action is not configurable from within the Microsoft Mail 3.x client, but is configurable when using Microsoft Exchange in two different ways:

1.	From within the Microsoft Exchange client. From the IMC property pages in Microsoft Exchange Administrator program.
2.	From the IMC property pages in Microsoft Exchange Administrator program.

Controlling the feature from within the Microsoft Exchange client:

This feature is manipulated using the Always Send to This Recipient in Microsoft Exchange Rich-Text Format (TNEF) checkbox. This property can be specified on a per recipient basis for several address types, including Internet addresses, when you define entries in the Personal Address Book (PAB).

You can also manipulate this per recipient property on a per message basis. This is convenient when you reply to Internet email or compose one-off messages to Internet recipients that aren't defined in the PAB. For additional information, please see the following article in the Microsoft Knowledge Base: Controlling the feature from the Microsoft Exchange Administrator program:

The Microsoft Exchange Administrator program provides manipulation of this property for all outbound mail via the IMC in two ways: Globally (all mail is encoded with the specified option), which overrides the originators selection, or per destination domain (messages sent to a specific domain are encoded using a specified option).

Each of these two considerations share three options:

1.	Encode based on whatever the originator has specified (User). [Always] send in Microsoft Exchange Rich Text format (TNEF). [Never] send in Microsoft Rich Text format.
2.	[Always] send in Microsoft Exchange Rich Text format (TNEF). [Never] send in Microsoft Rich Text format.
3.	[Never] send in Microsoft Rich Text format.

The global setting is found on the Internet Mail tab of the IMC properties page under Message Content Information, Sending Attachments Using, and the Interoperability button. In addition to specifying TNEF, the Microsoft Exchange administrator can specify other options such as the encoding method (MIME or UUEncode) and Character Set translation.

The same configuration details can be independently specified for specific target domains by adding an entry under the E-mail Domain button and defining the target domain name with the desired options.