Remove additional mailboxes from Outlook

Once you add an additional mailbox to Outlook, you might not be able to remove it receiving the message:
"This group of folders is associated with an e-mail account. To remove the account, on the Tools menu, click Account Settings, select the account, and then click Remove."

However, the account isn't listed there and you're unable to remove it. This happens because, annoyingly, while you can give yourself access to a mailbox, you can't actually remove the access as well. To really remove access you need to open ADSIedit and drill down to the user account who's mailbox you're trying to remove in Outlook, go the properties of their object, find the property called "MSExchangeDelegateListLink" and remove your account from it. Restart Outlook and after a couple of minutes the accounts will disappear.

Disabling computer password change

Windows 2003 and newer will regularly change their AD computer password. This can be troublesome if you ever have to restore a server from backup since the computer passwords can be out of sync and prevent the server from logging into the domain. While there are way to fix it after the fact, the only foolproof way to do it is removing the server from the domain and adding it back in, something which can cause all sorts of other problems. 

Personally, unless there is a compelling security reason not to, I disable computer password changes on my servers. It can make a stressful situation (restoring a server) from becoming even more stressful. To do so open the registry and navigate to and change DisablePasswordChange to 1:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters