Event ID - 9548

Event Id9548
Description Disabled user <user name> does not have a master account SID. Please use Active Directory MMC to set an active account as this users master account.
Event InformationExplanation :
An attempt to add a resource account to an Access Control List (ACL) failed because resource accounts do not have associated user accounts. See the events associated with this alert for specific resources.

A disabled user does not have a Master Account SID (attribute name is msExchMasterAccountSID). This can occur for several reasons, including but not limited to:

The Master Account SID could have been deleted directly using the Exchange Advanced user interface of the Active Directory Users and Computers snap-in.
The account may have been created incorrectly initially.
The account may have been partially deleted, with its mailbox rights removed but still retaining HomeMDB and other attributes.

User Action :
To keep and repair the account, do either of the following:

Use the Active Directory MMC to try and re-enable the account. If the account was created by the Active Directory Connector (ADC), then review the link "How to Enable Disabled Accounts That the ADC Creates".
Use the Active Directory MMC to assign another account with mailbox rights as the "external associated account" for the problem account. This could be simply the "Self" account for the damaged account.
To discard the damaged account, either completely delete the account or at least remove the HomeMDB attribute for it (this will make the account invisible to Exchange).
Reference LinksHow to troubleshoot public folder performance issues that are related to ACL conversions in Exchange 2000 and in Exchange 2003

Troubleshooting Public Folder Expansion Problems

Addressing Problems That Are Created When You Enable ADC-Generated Accounts

XFOR: Mail May Not Be Migrated from Novell GroupWise for Disabled User Accounts

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