Hi,

I'm in the process of migrating an Exchange 2003 domain to Office 365 and following the steps provided by the Office 365 team I've hit a problem with one mailbox when running a script which disables/disconnects the on-premise mailbox and converts the user to a mail-enabled user.

I asked the question here (https://social.technet.microsoft.com/Forums/exchange/en-US/612c159a-2d95-4659-b998-dc00d6f36392/converting-mailbox-user-to-mail-enabled-user-meu?forum=exchangesvrgenerallegacy) but was told that this might be a better forum to answer the question.

The script which Office 365 provided failed the first time it ran so when it re-ran the first user in the batch was skipped and has not been mail-enabled.  When I try to re-run the script (I've commented out the command to delete the mailbox as that has already been done) it fails with the error above when the user object is mail-enabled.

	'Mail Enable the User
	WScript.Echo "Opening " & userADSIPath & " as CDOEXM::IMailRecipient"
	Set MailUser = MyUser
	WScript.Echo "Mail Enabling user using targetAddress " & User.CloudEmailAddress
	MailUser.MailEnable User.CloudEmailAddress
	WScript.Echo "Disabling Recipient Update Service for user"
	MyUser.PutEx ADS_PROPERTY_APPEND, "msExchPoliciesExcluded", Array("{26491CFC-9E50-4857-861B-0CB8DF22B5D7}")
	WScript.Echo "Saving Changes"
	MyUser.SetInfo
	WScript.Echo "Refreshing ADSI Cache"
	MyUser.GetInfo

Can anyone tell me how I can mail-enable a user manually either via a script, modification of the user object via ADSIEdit or via ESM?

Hi Tippers,

You need to get hold of these values from the CSV or somewhere about the skipped mailbox first.

legacyExchangeDN   Value from the on-premises mailbox.
mail   The primary SMTP of the cloud mailbox.
proxyAddresses   Values from both the on-premises mailbox and the cloud mailbox.
targetAddress    Read from the on-premises mailbox; the value is the primary SMTP of the cloud mailbox.

You will need three attributes to populate to make a mail-enabled user object.  These mandatory attributes are:
 
*mailNickName
*DisplayName
*TargetAddress

Follow the steps mentioned in the "Mail enabled recipients" section of

Understanding Mailbox Enabled and Mail Enabled Recipients in Exchange 2003

or  'How to mail-enable a contact' part for User account without a mailbox

How to configure a mailbox to forward mail to a mail-enabled contact

Establish e-mail addresses: Will the the On-premises address mostlikely

Forwarding Address : Will have the O365 address

Compare the existing mail-enabled users to determine what goes where.

References:

Create a Mail-Enabled User Object for Exchange 2007/2010
http://social.technet.microsoft.com/wiki/contents/articles/5441.create-a-mail-enabled-user-object-for-exchange-20072010.aspx

Convert Exchange 2003 mailboxes to mail-enabled users after a staged Exchange migration
https://community.office365.com/en-us/w/exchange/834.convert-exchange-2003-mailboxes-to-mail-enabled-users-after-a-staged-exchange-migration

Bingo, I think it was the mailNickName property which was Not Set in ADSIEdit which prevented the user being seen as mail-enabled.  Once this was set it shows up.

Many thanks, now I can progress with my migration!