Event ID - 1209

Event Id1209
SourceMSExchangeMTA
DescriptionUnable to recognize an internal message identifier (LPI) from entity <object name>. The incorrect LPI is <value>-<value>-<value>. Control block index <index name>. [<value> <value> <value> <value>] (14)
Event InformationAccording to Microsoft:
CAUSE :

This behavior can occur if you use Fully Qualified Domain Names (FQDN) or NetBIOS names to configure the connectors.
RESOLUTION :
To resolve this behavior, on both Exchange servers, configure the X.400 Connector to use the IP address of the remote MTA, and then restart both MTAs.

This information from some newsgroups may help you:
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The OSI stack encountered an unexpected condition during communication with the transport layer. This usually indicates that a timing window closed during a connection. If the message flow is not affected, ignore the condition.

Refer following MS article for more information.
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Reference LinksNT Event Viewer messages.

 

XADM: MTA Reports Repeated Occurrence of Event Id 1209

XCON: Mail Not Flowing Through X.400 Connectors and Events 4282, 4283, 4284, 4287, 1209, and 1198 Occur

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