Exchange Resource Manager requires that the ERM Service Account is granted the "Log on as a batch job" right in the effective policy settings of the server running ERM. This happens automatically when ERM is installed, but if these rights are superceded by a Group Policy Object (GPO) it may cause ERM not to function. DCOM errors indicating an authentication failure are often seen in the Windows Application Event Log when meeting requests are sent to ERM-managed mailboxes given this scenario. In some cases, ERM may work for a period of time and then stop working at the point the inherited GPO is applied. See Microsoft KB article 312497 for more information on this requirement (http://support.microsoft.com/default.aspx?scid=kb;en-us;312497).

ERM uses the same functionality as MS Exchange so that if a user reschedules a resource and that request is declined (for whatever reason), MS Exchange will then delete the original meeting scheduled for the resource.

A refresh of the Exchange cache is necessary after managing a resource in order for the “Send As” rights granted to the Service Account to take effect. By default, this occurs every two hours. Any cancellations that occur after the Exchange cache has refreshed should occur normally.

Ensure that the password for the ERM service account is still valid. Attempt to verify the ERM service account from the ERM Mailbox Browser by clicking Edit -> Product Configuration -> Service Account tab -> Verify. Correct any pop up errors.

Check the System Event Log for DCOM errors with an event ID of 10004. Ensure that the ERM service account has “log on as a batch job” user rights in the effective local security policy setting for the server.

This is due to a problem with the mailbox store containing the resource mailboxes. Refer to the resolution steps in the following article: http://support.microsoft.com/default.aspx?scid=kb;en-us;316622. Either fix the existing store as described in the article or created a new store and move the resource mailboxes to newly created store.

The ERM Service account requires “Send As” rights to the resource account in order to correctly process cancelled meetings. ERM grants these rights as part of the management process, but it can take up to 2 hours for the new rights to take effect, since a refresh of the Exchange cache is necessary. Verify that the ERM Service account is granted “Send As” rights to the resource account (properties -> Security tab) in Active Directory Users and Computers. Allow two hours after management for these rights to take effect.