How to change the method for transfer encoding after you apply Exchange 2007 SP1 to the Exchange 2007-based server that is running the Hub Transport role

In Microsoft Exchange Server 2007, the 7-bit transfer encoding method for MIME format is fixed to Quoted-Printable (QP) encoding. After you apply Exchange 2007 Service Pack 1 (SP1) to the Exchange 2007-based server that is running the Hub Transport role, you can change the transfer encoding method by editing the EdgeTransport.exe.config file. This article describes how to change the method for transfer encoding.

Note The current scope includes five codepages: 50220, 50221, 50222, 50225, and 65000.

To change the method for transfer encoding, follow these steps:

1. On the Exchange 2007-based server that is running the Hub Transport role, open Windows Explorer.
2. Locate the following folder:
   drive:\Program Files\Microsoft\Exchange Server\Bin
3. Make a backup copy of the EdgeTransport.exe.config file by saving a version of it that is named EdgeTransport.exe.config.old.
4. Open the EdgeTransport.exe.config file in Notepad, and then locate the following line between the <appsettings> segment and the </appsettings> segment.

   <add key="ByteEncoderTypeFor7BitCharsets" value="1" />

   Note If this line does not exist between the <appsettings> segment and the </appsettings> segment, insert this line.
5. Change the value that is described in this line of code to an appropriate value from the following table. This change will control the MIME encoding behavior.
   
   Note The value should be written as a number. It should not be spelled out.

   Value	Behavior
   0	Always use default 7-bit transfer encoding for HTML and for plain text. Note This is the equivalent of setting Exchange to its pre-hotfix default behavior.
   1	Always use QP encoding for HTML and for plain text.
   2	Always use Base64 encoding for HTML and for plain text.
   5	Use QP encoding for HTML and for plain text unless line wrapping is enabled in plain text. If line wrapping is enabled, use 7-bit encoding for plain text.
   6	Use Base64 encoding for HTML and for plain text, unless line wrapping is enabled in plain text. If line wrapping is enabled in plain text, use Base64 encoding for HTML and 7-bit encoding for plain text.
   13	Always use QP encoding for HTML. Always use 7-bit encoding for plain text.
   14	Always use Base64 encoding for HTML. Always use 7-bit encoding for plain text.

6. Save the changes, and then exit Notepad.
7. Restart the Exchange Transport service.

Note The method that you use to change the transfer encoding does not affect the following MIME-format messages:

• Messages that are sent by an SMTP client, such as POP/IMAP
• Messages that come from an SMTP server that is not an Exchange Server 2007-based server, such as Sendmail, Qmail, Postfix, and so on
• Messages that come from an SMTP server that is an Exchange Server 2007-based server that is running the Hub Transport or Edge Transport role and that does not use the settings that are described in this article

For more information about the codepage identifiers, see the following Microsoft Web site: For more information about Exchange 2007 SP1, visit the following Microsoft Download Center Web site: For more information about problems with formatting in an e-mail message, click the following article number to view the article in the Microsoft Knowledge Base: