Environment is Windows 2003 DC's with Exchange Exchange2003 but transitioning to 2010SP1. On 2010, CAS/HUB role is mail01. MBX role is mail02. A name typo caused a third machine to be joined to the domain also as mail02. This duplicate mail02 was renamed mail03 and rebooted. Original mail02 was then rebooted but then threw error "security database on the server does not have a computer account for this workstation" when trying to log on. Renamed mail03 was then removed from the domain and powered off. ADUC showed red X on mail03. Original mail02 was rebooted again but still threw the error so it was removed and re-added to the domain. At this point the mailbox server appears hosed. After over 20 minutes sitting at "applying policy" and whatnot at logon, it's not coming back. Is there a way to get mail02 back to a functioning state without restoring from a (non-existent) backup at this point?

Do you have System State backup from before the third machine was joined? Restore System State on your DC and you should be back to working. Now you will have to rejoin again the mail03 server again since it did not exist at the time the system state backup was taken.MVP Exchange Server

You may try this: take a backup of both AD and the exchange server so that you can restore to this point if things get worse rebuild the broken exchange server using the setup.com /recoverserver option (http://technet.microsoft.com/en-us/library/dd876880.aspx) Mike Crowley Check out My Blog!

You may try this: take a backup of both AD and the exchange server so that you can restore to this point if things get worse rebuild the broken exchange server using the setup.com /recoverserver option (http://technet.microsoft.com/en-us/library/dd876880.aspx) Mike Crowley Check out My Blog! This looks promising... Would it likely keep the data within in the mailbox database when doing the recover back to that same server?

No, you'd need to backup the mailbox database and restore it later. This will recover the server's configuration from AD - not it's data. I'm not positive it will work considering its AD that's messed up in the 1st place. This may be a job for microsoft support. Mike Crowley Check out My Blog!

No, you'd need to backup the mailbox database and restore it later (or reseed). This will recover the server's configuration from AD - not it's data. I'm not positive it will work considering its AD that's messed up in the 1st place. This may be a job for microsoft support. Mike Crowley Check out My Blog!

Microsoft support was able to help sort it. Basically disconnected the NIC then signed on to local admin account and disabled Exchange services. Reconnected NIC, signed on as domain admin. Removed/re-added mail02 to the domain. Then re-ran schema update and preparead from Exchange setup. Then put mail02 back in to the approrpriate Exchange Servers AD groups and re-enable the Exchange services. The mailbox data was there when all was finished along with queued items.