Some clients cannot connect to back-end Exchange Server 2003 IMAP servers after Exchange 2007 Service Pack 1 RU2 is applied

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Article ID: 959861 - View products that this article applies to.
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SYMPTOMS

Microsoft Exchange Server 2007 Service Pack 1 (SP1) Rollup 2 (RU2) provides support for PLAIN authentication in both POP3 and IMAP4 services. However, PLAIN authentication cannot be disabled. Therefore, POP or IMAP users who use PLAIN authentication will be unable to connect to back-end Microsoft Exchange Server 2003 mailbox servers through Exchange 2007 CAS.

For more information about Update Rollup 2 for Exchange Server 2007 Service Pack 1, see the following Exchange Help topic:
Description of Update Rollup 2 for Exchange Server 2007 Service Pack 1

RESOLUTION

To resolve this problem, install Update Rollup 8 for Exchange 2007 Service Pack 1.

For more information about Update Rollup 8 for Exchange Server 2007 Service Pack 1, see the following Exchange Help topic:
Description of Update Rollup 8 for Exchange Server 2007 Service Pack 1
For more information about how to obtain the latest Exchange service pack or update rollup, see the following Exchange Help topic:
How to Obtain the Latest Service Pack or Update Rollup for Exchange 2007
After you apply this rollup, when a POP or IMAP user sends PLAIN authentication requests, Exchange 2007 servers will use a proxy server and LOGIN authentication to connect to Exchange Server 2003 back-end servers.

STATUS

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

MORE INFORMATION

For more information about PLAIN authentication, visit the following RFC Web sites:
http://www.ietf.org/rfc/rfc4616.txt

http://www.ietf.org/rfc/rfc2595.txt

Properties

Article ID: 959861 - Last Review: July 13, 2009 - Revision: 2.1
APPLIES TO
  • Microsoft Exchange Server 2007 Service Pack 1, when used with:
    • Microsoft Exchange Server 2007 Enterprise Edition
    • Microsoft Exchange Server 2007 Standard Edition
Keywords: 
kbexpertiseinter kbexpertiseadvanced kbqfe kbsurveynew kbhotfixrollup KB959861

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