Script converting Mail-User to Mailbox-User

Not all organizations need to have every user to be mailbox-enabled, sometimes a mail-user (also referred to as mail-enabled user) with a forwarding SMTP address to an external mailbox is enough. However, it is surely possible that the requirements over time change and the mail-enabled user does need to be mailbox-enabled, making use of the calendar or perhaps even more efficient use of Lync integration.

However, converting a mail-user isn’t just changing the RecipientType of the account. First the users needs to be mail-disabled, most importantly it then looses all the configured SMTP addresses and the forwarding address. Then the user has to be mailbox enabled and all SMTP addresses that aren’t added via an Email Address Policy have to be manually added. Optionally, one can configure the mailbox to be forwarding to the external SMTP address.

To make this process somewhat more manageable, I created a script that converts a mail-user to mailbox-user. It keeps all configured SMTP addresses, when they correspond with an accepted domain (otherwise it will be discarded). The exception is the configured External SMTP address, it is optional to keep forwarding mail.

The syntax is depicted below:

Convert-MailUser –Identity <UserIdParameter> [-KeepForwarding]

The mail user will be mail disabled without a need for confirmation. The parameter -Identity is mandatory and a string. Accepted formats are:

• User Principal Name
• Display Name
• Distinguished Name (DN)
• Domain\Account
• GUID

The switch [–KeepForwarding] is optional. This switch will retain the SMTP Forwarding address from the mail-user and will add it as an ForwardingSMTPAddress, with mail being forwarded to that address and sent to the Exchange Mailbox. No additional value (like $true/$false etc.) is required.

Please note that the ForwardingSMTPAddress value does not show up in the Exchange Admin Center view at the moment (Exchange 2013RTM CU1). You will have to use the Exchange Management Shell (Get-Mailbox|fl) to check whether the Mailbox is forwarding mail to an external address.

You can download this script from the TechNet Gallery.

Note: This script has been tested on Exchange 2013 on Windows Server 2012, but will probably work on 2010 and 2007 and Windows 2008 R2. Use at your own risk and the script is provided as-is.