XADM: Event Scripts Fail with Error 0x800401f0 (CO_E_NOTINITIALIZED) after Installing Exchange 5.5 SP2

After you install Exchange Server 5.5 Service Pack 2 (SP2), applications that use Cdo.dll may start receiving an error of 0x800401F0 (CO_E_NOTINITIALIZED) indicating that CoInitialize() has not been called. The most common environment where this may be seen is with event scripts that run using the Microsoft Event Service. This problem will typically be seen with event scripts that log on to a new MAPI session from within the script.

The application event log may show events that look similar to the following:

Changes were made in Exchange Server 5.5 SP2 to allow Cdo.dll to properly support the Component Object Model (COM) Multi-Threaded Apartment (MTA) model. The Microsoft Event Service exposed a problem with these changes.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The English version of this fix should have the following file attributes or later:

Component: MAPI

Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5 Service Pack 2. This problem was first corrected in Exchange Server 5.5 Service Pack 3.