Some message parts are not readable when Exchange Server 2007 must convert the message part encoding from binary or from 8 bit to 7 bit

In a Microsoft Exchange Server 2007 environment, you send a message that has multiple MIME parts and the Content-Transfer-Encoding (CTE) of the root part is set to binary or is set to 8 bit. If the remote server does not support SMTP protocol extensions such as the BDAT command, some parts of the message are not readable.

Note A typical example of this scenario can be seen when Exchange Server 2007 archives the journaling messages to external non-Exchange mail servers.

This problem occurs because Exchange Server 2007 must convert the message encoding from binary or from 8 bit to 7 bit if the remote server does not support SMTP protocol extensions. During the conversion process, Exchange Server 2007 correctly detects the base64 or Quoted-Printable (QP) encoding of a file part and reads the body part through the corresponding decoder. However, Exchange Server 2007 assumes that the part is still encoded in base64 or in QP when the message is sent, and do not encode the part again. Therefore, some parts of the message are marked as Base64 or as QP without actually being encoded. When this behavior occurs, the affected parts of the message are no longer readable.

To resolve this problem, install the following update rollup:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about Content-Transfer-Encoding, visit the following Microsoft Web site:

For more information about SMTP protocol extensions, visit the following Microsoft Web site: