Event ID - 12004

Event Id12004
DescriptionError <error code> occurred while processing message <message id>. The archive filename is <file name>.
Event InformationAccording to Microsoft:
When two sites have an identical custom recipient, directory replication between the sites creates duplicate entries in the global address list. For example, if someone@microsoft.com exists in site X and someone@microsoft.com exists in site Y, upon site replication between the sites, the global address list will have two identical entries, resulting in ambiguous names.
When the Internet Mail Service submits the message to the Microsoft information store, and the ResolveP2 registry key is enabled, a directory lookup on the sender is submitted to the directory service. The directory service finds duplicate entries, and this creates an ambiguous condition because there is more than one address that meets the criteria. This error then is mapped as E_FAIL, resulting in the above error logs, and message is archived in the archive directory.
A supported hotfix is now available from Microsoft intended to correct the problem.Apply it only to systems that are experiencing this specific problem.You must restart your computer to apply the changes after you install this hotfix.
Reference LinksXADM: IMS/STORE Incorrectly Archives Message If ResolveP2 Is On

Event IDs 4118 and 12004 appear in the Application log, and e-mail messages are not delivered to recipients in Exchange Server 5.5

XFOR: Information Store Incorrectly Archiving a Message If ResolveP2 Is Enabled

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