Event ID : 8231

Issue : Exchange Recipient Update Service does not stamp proxy addresses in Exchange 2000 Server and in Exchange Server 2003.

Event Source: MSExchangeAL

Cause : The Microsoft Exchange 2000 Server or Microsoft Exchange Server 2003 Recipient Update Service does not create proxy addresses (e-mail addresses) for newly mail-enabled users or public folders when the computer that is running Exchange is in an Exchange mixed-mode environment. An Exchange mixed-mode environment includes Exchange Server 5.5 and Exchange 2000 Server or Exchange Server 2003.

Description : Recipient Update Serivce not stamping email address on newly created mailboxes.
Permanent failure reported by policy group provider for 'CN=Recipient Policies,CN=Name,CN=MicrosoftExchange,CN=Services,CN=Configuration,DC=Name,DC=com':'MAD.EXE', error=8000ffff. Taking provider offline.

Action Required : To resolve this issue, either manually copy the missing .dll file from an existing Exchange Server 5.5 computer, or disable that particular address type so that the Recipient Update Service no longer tries to load the .dll file.

Ref Link:
http://support.microsoft.com/kb/288807/en-us
http://support.microsoft.com/kb/286356/en-us