Deploy hybrid Exchange Servers into a production environment


Applies to: Office 365 Enterprise

Topic Last Modified: 2013-11-12

Summary: Describes the process of putting your hybrid servers into production mode by changing the MX record to redirect mail flow to Office 365.

When you are ready to put your hybrid servers into production, you need to change your MX record to redirect inbound mail flow to an on-premises hybrid Hub Transport server or a server that is running Exchange Server 2010 with Service Pack 2 (SP2) and is deployed with the Edge Transport server role.

For cutover or staged migrations, you may refer to the steps below.

For Hybrid deployments, the Exchange Server Deployment Assistant provides detailed steps for changing the MX record in the customized checklist for your configuration.

If you haven’t done so already, you can update your email delivery settings so that all email sent to your primary domain goes to your new Exchange Online service in the cloud. Before you configure DNS for email delivery, consider your overall deployment plan to Office 365:

  • If you plan on deploying SharePoint Online and Lync Online immediately, you should consider configuring those services before you complete your DNS email configuration. This is so that all of the cloud services are configured and ready before you tell your users to logon to the cloud the first time.

  • If you plan on configuring SharePoint Online and Lync Online later, then you can configure DNS for email delivery now, then inform your users. You can come back and set up SharePoint Online and Lync Online any time.

To direct all the incoming email for your domain to Office 365 for enterprises, you have to create a specific MX (mail exchanger) record at your domain's DNS hosting service.

The MX record you create must contain the following information:

Host: @

Points to address: Office 365 mail server (for example, See the steps below.

Preference/Priority: 0 (or High)

TTL: 1 hour

To find the specific points to address you need to use, do the following.

  1. In Office 365, go to Admin > Domains.

  2. Select the domain you’re working with, and then click View DNS settings.

  3. In the Exchange Online table, find the row for MX records.

  4. Use the points to address in the MX record row to create the record at your domain’s DNS hosting service.

When you create the MX record, to avoid typos, copy and paste the information from the table in DNS settings to the data entry form for your DNS hosting service.

Be sure to remove any existing MX records for your domain.

Typically it takes about 15 minutes for your changes to take effect. But it can take up to 72 hours for the record that you created to propagate through the DNS system.

If you’re migrating data, until you change your MX record, e-mail sent to users is still routed to their on-premises Exchange mailboxes. After a mailbox is successfully migrated, the incremental synchronization process synchronizes the on-premises Exchange mailbox and cloud-based mailbox once every 24 hours until you delete the migration batch. When you configure your organization's MX record to point to your cloud-based e-mail organization, all e-mail is sent directly to the cloud-based mailboxes.
After you change the MX record and verify that all e-mail is being routed to the cloud-based mailboxes, you're ready to delete the migration batch.