XCON: Illegal Country Code in X400 Address Causes MTA to Hang

The Microsoft Exchange message transfer agent (MTA) may stop responding after logging content conversion error messages similar to the following:

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 problem occurs when the Exchange MTA receives a message from a foreign MTA that has an illegally formed X400 address containing a country code with a single character. All X400 country codes must be either two or three characters long.

The MTA hangs when it attempts to perform content conversion on the message containing the invalid address. The Microsoft Exchange version 4.0 SP1, SP2, SP3, and SP4 MTA will not log content conversion failures to the BF0.LOG files if APDU logging is enabled. However, the Microsoft Exchange version 5.0 MTA will log content conversion errors to the BF0.LOG files if APDU logging has been enabled. This functionality has also been added for all 4.0 MTAs starting with build 996.18 which is a post SP4 build. This feature is extremely desirable since it allows messages that fail content conversion to be logged to the APDU logs in order to determine the cause of the failure. APDU logging is enabled by setting APDU logging to maximum and X.400 Service logging to minimum.