Relay specific Exchange Mailbox to defined SMTP host

I would like to relay a specific Exchange 2010 Mailbox to an external SMTP host, in this case Office 365, as we're migrating user by user to Office365. Meaning if the migrated users receives an e-mail, it should be automatically redirected to the defined host (Office365).

In Postfix this is really simply done by using the transport map /etc/postfix/transportmap:

[email protected]       smtp:[domain.mail.protection.outlook.com]

Any ideas how this could be implemented using Exchange 2010? Exchange Transport Rules don't have any action available for this scenario.

Thank you in advance for your help!

In Exchange you need to create a mail enabled smtp contact, then after in the account mailflow you forward to that external's contact.

How to configure mail forwarding Note The forwarding address can be any mail-enabled object. Examples of mail-enabled objects include distribution groups, security groups, public folders, and other related items.

• Start the Active Directory Users and Computers snap-in.
• Right-click the mail-enabled user, and then click Properties.
• Click the Exchange General tab.

• Click Delivery Options.

  • In the Forwarding Address section, click Forward to, and then click Modify.
  • Click the mail-enabled user or the mail-enabled contact. Then, click OK.

  Note If you want e-mail to be delivered to the original mailbox as well as the forwarding address, select the Deliver messages to both forwarding address and mailbox check box. To close Delivery Options and to close Properties, click OK two times.

Took from there How to configure a mailbox to forward mail to a mail-enabled contact