XFOR: IMC Appears Hung with Improper DN Format

• Microsoft Exchange Server, versions 4.0 and 5.0

SYMPTOMS

The Internet Mail Connector (IMC) or Internet Mail Service may stop processing mail and a mail backlog may build in the connector's mailbox in the Information Store (MTS-OUT).

Under the debugger, the connector's threads appear inactive and waiting on a critical section.

CAUSE

An improperly formatted distinguished name (DN) causes the IMC or IMS to overwrite memory and corrupt the heap.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 5.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K

MORE INFORMATION

This is a very isolated case in which a third-party product, Baranof's MailCheck, was set up with a DN that looked like the following:

   /O=ORGNAME=OU=SITENAME

With the fix applied, the IMC or IMS validates the DN before writing it into memory.

MailCheck is manufactured by Baranof's, a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.