How to grant/remove permissions on an Exchange 2007 mailbox

These almost-daily tasks are quite easy to perform via EMC, but infinitely easier through PowerShell...

Adds mailbox permissions:
Add-MailboxPermission -Identity MAILBOX -User USER -AccessRights FullAccess -InheritanceType All

Removes mailbox permissions:

Remove-MailboxPermission -Identity MAILBOX -User USER -AccessRight FullAccess -confirm:$false

Most used parameters:

• Identity: the username or email address associated to the mailbox which you want to set the permissions
• User: the username or email address associated to the user who will receive the permissions on the mailbox
• InheritanceType: specify how far down the Active Directory object structure the “read” permissions are inherited (more info here)
• AccessRights: the rights you want to grant to the user on the mailbox. Valid values are: 
• FullAccess; 
• SendAs; 
• ExternalAccount; 
• DeleteItem; 
• ReadPermission; 
• ChangePermission; 
• ChangeOwner
• Confirm: Specifies whether the command will pause and wait for your confirmation when removing an user's permissions. Set it as $True if you want the script to run without requesting confirmation.

UPDATE: See also the post How to get mailbox permissions about getting the permissions on a mailbox

More info:

Add-MailboxPermission cmdlet

Remove-MailboxPermission cmdlet