I apologize in advance if this comes across unclear, as I'm new to this company and the issue most likely derives from something long before my time and may be leaving out some key information. We are getting traces in event logs in one of our domains containing an OU that does not exist - at least, no longer exists. The event is as shows: Event Type: Error Event Source: MSExchangeIS Mailbox Store Event Category: Logons Event ID: 1022 Date: 7/3/2006 Time: 2:30:55 AM User: N/A Computer: BRMX01 Description: Logon Failure on database "First Storage Group\Mailbox Store (_mailservername_)" - Windows 2000 account NT AUTHORITY\SYSTEM; mailbox /O=xxxxx_xxxxxx/OU=xxxx_xxxxx/cn=Recipients/cn=flowersa. Error: -2147221231 Event Id 1022 Source MSExchangeIS Mailbox Store Description Logon Failure on database "First Storage Group\Mailbox Store (MURPH4)" - Windows 2000 account NT AUTHORITY\SYSTEM; mailbox /o=First Organization/ou=First Administrative Group/cn=Recipients/cn=SystemMailbox{79A2634C-6491-45A0-8C5C-16ACB8C4FEEE}. Error: -2147467259 For more information, click http://www.microsoft.com/contentredirect.asp. Event Information As per Microsoft: To resolve this issue, manually rebuild the Recipient Update Service (RUS) so that every user object receives the correct attributes. To rebuild the Recipient Update Services follow these steps: Open Exchange System Manager. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager. Expand Recipients, and then expand Recipient Update Services. In the right pane is a list of all Recipient Update Services, in this pane right-click each Recipient Update Service, one at a time, and then click Rebuild. See the link below. Links Q273448 Reference Links XCCC: Outlook and Outlook Web Access Cannot Log On After Upgrade From my understanding, these "remnants" are from an Exchange 5.5 organization on an NT domain and probably are still rearing their head due to some issue with an upgrade from Exchange 5.5 to 2000 severalyears ago. It seems to me that the "Event Information" is pointing to a recipient being "orphaned". However, that recipient does not exist any longer. Basically, we're trying to get rid of these instances from an Exchange organization that no longer exists. I cant figure out why we're still seeing traces of the old organizationin our event logs when the user/mailbox no longer exists and cant be found in ESM or AD. Clear as mud?If I can provide any further information to help, I will.