Exchange 2007 may change the code page of MIME e-mail messages when the messages are downloaded by using a POP3 client or by using an IMAP4 client

In a Microsoft Exchange Server 2007 organization, Exchange 2007 may change the code page of MIME e-mail messages when messages are downloaded by using a POP3 client or by using an IMAP4 client. Messages that originally used a multibyte character set such as UTF-8 or UTF-7 may be re-encoded to use a single-byte codepage that contains all the characters that are used in the message. This behavior becomes a problem if the following conditions are true:

• Two or more code pages satisfy the selection criteria.
• An incorrect code page is selected as the intended final code page.

Example 1

A message that contains only Turkish and Latin characters may be encoded with either the ISO-8859-3 code page or the ISO-8859-9 code page. If the message is encoded with the ISO-8859-3 code page, a client that has the ISO-8859-9 code page available but not the ISO-8859-3 code page would be unable to display the message.

Example 2

A subset of Unicode characters belongs to both the GB2312 (CHS) code page and the ISO-2022-jp (JPN) code page. If a message is composed by using the UTF-8 code page, the message may be re-encoded with the ISO-2022-jp codepage. If the message is encoded with the ISO-2022-jp code page, a client that has the GB2312 code page available but not the ISO-2022-jp code page would be unable to display the message.

To resolve this problem, install Microsoft Exchange Server 2007 Service Pack 1 (SP1). For more information, click the following article number to view the article in the Microsoft Knowledge Base: Note After you install Exchange 2007 SP1, the Exchange 2007 server preserves the original multibyte encoding of e-mail messages.

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

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the naming schema for Exchange Server software updates, click the following article number to view the article in the Microsoft Knowledge Base: