You turn off the 8bit-MIME setting and the binary-MIME setting on a Microsoft Exchange Server 2010 Hub Transport server.
An email message is sent through the Hub Transport server to a remote mail server.
This email message contains embedded messages.
In this scenario, the embedded messages are corrupted when the recipient opens the email message.
This issue is caused because the affected embedded messages contains Content-Transfer-Encoding (CTE) values in binary or in 8bit. These CTE values must be downgraded to 7bit. Additionally, there is at least one MIME part encoded in BASE64 or encoded in Quoted-Printable. During the conversion process, a logic issue results in the corrupted MIME part.
To resolve this problem, install the following update rollup:
982639 Description of Update Rollup 4 for Exchange Server 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about MIME, visit the following website: