Outlook cannot connect to Exchange Server 2010 RC using POP3

Just installed Exchange Server 2010 RC and when trying to test it with my outlook in POP3 configuration I received this error:

"Task 'user@domain.com - Receiving' reported error (0x800CCC0F) : 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).'"

The problem was that for some reason after installing Exchange Server 2010 RC, service Microsoft Exchange POP3 did not start automatically, so I had to open services.msc (via "run"), and start this service manually, also changed its startup type to Automatic for future. This solved the problem.

Outlook cannot connect to Exchange Server 2010 RC using IMAP

Just installed Exchange Server 2010 RC and when trying to test it with my outlook in IMAP configuration I received this error:

"Task 'Synchronizing subscribed folders for user@domain.com.' reported error (0x8004DF0B) : 'Outlook cannot synchronize subscribed folders for user@domain.com. Error: The connection to the server is unavailable. Outlook must be online or connected to complete this action. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).'"

The problem was that for some reason after installing Exchange Server 2010 RC, service Microsoft Exchange IMAP4 did not start automatically, so I had to open services.msc (via "run"), and start this service manually, also changed its startup type to Automatic for future. This solved the problem.

Uninstalling Exchange Server 2010 RC, Mailbox role prerequisites error:

Tried to uninstall Exchange 2010 RC and encountered this error:
"Uninstall cannot continue. Database 'Mailbox Database 0186314254': This mailbox database contains one or more mailboxes or arbitration mailboxes. To get a list of all mailboxes in this database, run the command Get-Mailbox -Database . To get a list of all arbitration mailboxes in this database, run the command Get-Mailbox -Database -Arbitration. Before you can remove this mailbox database, you must disable, move, or remove user mailboxes and move arbitration mailboxes. "

So I removed the user maibloxes, but had no idea how to remove arbitration mailboxes, after some googling here is what I did:
in Exchange Management Shell
Get-Mailbox -Arbitration | Remove-Mailbox -Arbitration -RemoveLastArbitrationMailboxAllowed
this should remove all arbitration mailboxes.

Or you can do the following
get-mailbox -arbitration | fl name, identity

After you get the ID of those mailboxes you can remove them one by one with the following command:
remove-mailbox -identity "domain.com/Users/SystemMailbox{1f05a927-563f-4671-8a1b-487764400889}" -arbitration -RemoveLastArbitrationMailboxAllowed

If all went smooth you can try uninstalling Exchange Server.

Links: http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/d058717e-bf70-4449-91c2-fa00b47d415f

Microsoft File Transfer Manager queue keeps on restoring when you relaunch FTM

If you can't get rid of files in FTM queue try navigating to C:\Users\you_username\AppData\Roaming\Microsoft\File Transfer Manager
and delete file "ftmTransferList.txt". Next time you launch FTM they should not reappear.

Can't uninstall Exchange 2007 SP1 Mailbox role from Server 2008 R2

If you are getting error:
"An error occurred. The error code was 3221685466. The message was The service is already registered.."
while trying to uninstall Exchange 2007 SP1 Mailbox role from Server 2008 R2 (RC in my case)
try changing registry key value from "Uninstall" to "Install" located at
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Exchange\v8.0\Mailbox\
after that try uninstalling again.