Zix Smart Host Office 365

This how-to is for Office 365 after the May 2015 update. This is the procedure for adding a smart host and enabling outbound filtering.
Step-by-step guide

1. Login into the Office 365 Admin Center
2. Select Exchange under the Admin section in the menu on the left
3. Select Mail Flow
4. Select Connectors
5. On the Connector screen, select the plus sign to add a new connector
6. On the “Select your mail flow scenario” screen, choose From: Office 365 To: Partner Organization, then click Next
7. Name the Connector, i.e Zix Gateway, then click Next
8. Choose “Only when email messages are sent to these domains”
9. Click the Plus sign. Enter * as the domain and click OK, then click Next
10. Choose “Route email through these smart hosts”
11. Click the Plus sign. Enter the FQDN for your smart host then click Save.

zixcX.strongport.com <<---where X is the Zix cluster your domain was provisioned in.

12. Click Next again
13. Check "Always use TLS to secure this connection.
14. Check "Any digital Certificate including self signed certificates
15. Click Next again
13. Click the Plus sign and enter an email address that is NOT an Office 365 address on the same account then click OK, then click Next
14. Click Validate
15. Office 365 will now attempt to connect to the smart host and send a test message. If both tests are successful, click Save. Outgoing mail will now be routed through the Email Protection service.

NOTE: If there are multiple outbound connectors Enabled in O365, they may need to Disable all but the Zix Connector for the Validation to run successfully.