Empty All Exchange 2007 Mailboxes

The Problem

Today, I needed to remove all the mail from every mailbox on an SBS 2008 Exchange server, mostly because I didn't really like that the server sent a welcome email to each user giving them links to things we won't be implementing. After a lot of Googling, I found the PowerShell command "Export-Mailbox" can do this for me. When I ran the command, I ran into some errors that weren't very useful:

Command I ran: Get-Mailbox | Export-Mailbox -DeleteContent

Error:

StatusMessage                    : Error occurred in the step: Moving messages.
                                    Failed to copy messages to the destination
                                   mailbox store with error:
                                   MAPI or an unspecified service provider.
                                   ID no: 00000000-0000-00000000
ReportFile                       : C:\Program Files\Microsoft\Exchange Server\L
                                   ogging\MigrationLogs\export-Mailbox20090819-
                                   104007-5727927.xml

The Solution

So after quite a while of more Googling, I found that this generic and almost useless error message is telling me that I don't have permission to the mailbox in the first place, so I can't delete any of the messages. Despite my being Administrator, here's what I did to get past this issue altogether.

1. Right click the Exchange Management Shell, and select Run as Administrator (this is a handy trick).
2. Type the command "Get-Mailbox | Add-MailboxPermission -accessrights fullaccess -user Administrator" - if prompted, apply to ALL objects.
3. Type the command "Get-Mailbox | Export-Mailbox -DeleteContent" - if prompted, apply to ALL objects.
4. Type the command "Get-Mailbox | Remove-MailboxPermission -accessrights fullaccess -user Administrator" - Select "NO" when prompted about the Administrator mailbox! You can select "YES" for all other mailboxes, or apply to all if you want.