MIMESupport (Sync)

The MIMESupport element is an optional child element of the Options element in Sync command requests that enables MIME support for email items that are sent from the server to the client.

Elements referenced in this section are defined in the AirSync namespace, except where otherwise indicated by the presence of a namespace prefix (as defined in section 2.2.4).

Command request/response

Parent elements

Child elements

Data type

Number allowed

Sync command request (section

Options (section


unsignedByte ([MS-ASDTYPE] section 2.8)

0...1 (optional)

The following table shows valid values for the element. If the MIMESupport element is not present, the default value of 0 is used.




Never send MIME data.


Send MIME data for S/MIME messages only. Send regular body for all other messages.


Send MIME data for all messages. This flag could be used by clients to build a more rich and complete Inbox solution.

The client MUST send a maximum of one MIMESupport element. The result of including more than one MIMESupport element as the child element of the Options element is undefined. The server MAY return a protocol status error in response to such a command request.

The Sync request MUST include the following elements in the Options element when handling S/MIME content:

§ The MIMESupport element to tell the server to return MIME for S/MIME-only/All/None messages.

§ The airsyncbase:BodyPreference element ([MS-ASAIRS] section with its child element, airsyncbase:Type ([MS-ASAIRS] section, which contains a value of 4 to inform the server that the device can read the MIME BLOB.

When handling S/MIME content in the response, the server MUST include the airsyncbase:Body element ([MS-ASAIRS] section, which is a child of the ApplicationData element (section The airsyncbase:Body element is a complex element and MUST contain the following child elements in an S/MIME synchronization response:

§ The airsyncbase:Type element ([MS-ASAIRS] section with a value of 4 to inform the device that the data is a MIME BLOB.

§ The airsyncbase:EstimatedDataSize element ([MS-ASAIRS] section to specify the rough total size of the data.

§ The airsyncbase:Truncated element ([MS-ASAIRS] section to indicate whether the MIME BLOB is truncated.

§ The airsyncbase:Data element ([MS-ASAIRS] section that contains the full MIME BLOB.

For more details about the airsyncbase:Body element or the airsyncbase:BodyPreference element, see [MS-ASAIRS] section or [MS-ASAIRS] section, respectively.

Protocol Versions

The following table specifies the protocol versions that support this element. The client indicates the protocol version being used by setting either the MS-ASProtocolVersion header, as specified in [MS-ASHTTP] section, or the Protocol version field, as specified in [MS-ASHTTP] section, in the request.

Protocol version

Element support















This section provides details about using the airsyncbase:BodyPreference element, the airsyncbase:Body element, and the child elements of these elements when handling S/MIME content. Protocol version 2.5 does not support these elements. If protocol version 2.5 is used, the server uses the email:MIMEData, email:MIMETruncated, and email:MIMESize elements, as specified in [MS-ASEMAIL], when returning MIME data.