How to remove Exchange 2003 Mailbox Manager settings without the 2003 Management Console

I'm doing an Exchange 2007 to Exchange 2010 migration for a client and found that the Address Lists and E-mail Address Policy had not been updated from Legacy Exchange 2003 policies when they upgraded to 2007.  Typically, these are converted from Legacy policies in Exchange 2007 or 2010 by adding an RecipientFilter OPATH filter.

Exchange 2003 Mailbox Management policies were replaced by Messaging Records Management (MRM) in Exchange 2007.  During the migration from Exchange 2003, you're supposed to create new MRM policies to match your Exchange 2003 Mailbox Manager polices and then remove the 2003 policies using the Exchange 2003 Management Console.

The customer didn't do this before Exchange 2003 was decommissioned, so I'm doing it now in the 2010 migration.  But as I tried to convert the Default Policy in E-mail Address Policies using the Set-EmailAddressPolicy "Default Policy" -IncludedRecipients AllRecipients command, I get the following error:

Set-EmailAddressPolicy : The recipient policy "Default Policy" with mailbox manager settings cannot be managed by the current version of Exchange Management Console. Please use a management console with the same version as the object.
At line:1 char:23
+ Set-EmailAddressPolicy  <<<< "Default Policy" -IncludedRecipients AllRecipients

This happens when the Default Policy also includes Mailbox Manager settings.  Since there are no Exchange 2003 servers anymore (or 2003 console) in this environment, I can't remove the Mailbox Manager settings from the policy.  Here's how to fix this using ADSI Edit:

• Run ADSI Edit from the Exchange 2010 server.
• In the Configuration container, navigate to CN=Recipient Policies,CN=<Exchange Org>,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=<domain>,DC=<com>
• In the middle pane, view the properties of the Default Policy.
• Remove the value(s) of the MsExchMailboxManagerFolderSettings attibute so that it's now <Not Set>
• Edit the MsExchPolicyOptionList attribute and remove all the attributes that do not begin with 0xfc.  The policy that begins with 0xfc is the email addressing policy.

Now when you run Get-EmailAddressPolicy "Default Policy" | FL you will see that HasMailboxManagerSetting is set to False and you will be able to update the Default Policy.