The domain controller replication intersite messaging service received an SMTP message in its drop directory which could ...

The domain controller replication intersite messaging service received an SMTP message in its drop directory which could not be processed. The message was addressed incorrectly or was in a format which it did not recognize. It could also be that the Intersite Messaging Service (ISMSERV) was unable to accept the message because it was not running. The message was deleted. 
 
Client IP Address: 
%1 
Subject: 
%2 
 
User Action
 Verify that the Intersite Messaging Service (ISMSERV) is running. Check for misconfigured applications that may be sending mail to the domain controller's guid-based mail address. 
 
Additional Data 
Reason value:
%3 %4