XFOR: IMC Appears Hung with Improper DN Format

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.

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

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 4.0. This problem has been corrected in the latest U.S. Service Pack for Microsoft Exchange Server version 4.0. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):
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):

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: A proper DN should look like /O=ORGNAME/OU=SITENAME. Baranof's software does not check the validity of the DN when entered during the product's setup. As a result, messages sent from MailCheck contain this incorrect DN and caused the IMC to seem to stop responding.

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.