As per Microsoft: "This event indicates that there was an internal error. This can occur if the message transfer agent (MTA) database is corrupt or the MTA DAT files are not accessible". See MSEX2K3DB
for additional information about this event.
This may occur if the System Account or LocalSystem Account is specified as the service account in Control Panel Startup for each of these services. There are several Microsoft articles with information about this event: ME159307
When an MTA object is created, its reference count is initialized to one. When the object is passed to an entity that can delete the object, the reference count must first be incremented. When an object deletion is requested, the reference count is decremented (and when the reference count for the object reaches zero, the object is physically deleted). There is a race condition in the MTA, where a newly initialized object (reference count of one) is passed to an entity (the Microsoft Exchange Internet Mail Connector) before the reference count is incremented. An object deletion is requested by the Internet Mail Connector (IMC) (which decrements the reference count to zero, and causes the object to be deleted). When the MTA attempts to access the object, the object had already been deleted and an "ODXOINIU - Object does not exist" complaint is raised by the MTA.