Outbound Security setup for Microsoft 365: Segmented mail routing by domain

This configuration can be used to direct email from a subset of domains out via Paubox, rather than directing all email traffic from your organization out via Paubox. This is done in the Microsoft 365 Exchange Admin Center by creating an outbound connector and transport rule. 

Note: The complete setup instructions for Outbound Security setup for Microsoft 365 are here. The  configuration below can be used in place of Part II: Microsoft 365 - Create a Connector.

A Paubox subscription or trial subscription is required (don't have one? sign up here!)

Questions? Stuck? We’re here for you!  support@paubox.com

Step-by-step guide

Part I: Create a connector     

1. in to the Microsoft 365 Exchange Admin Center using admin-level credentials (https://admin.exchange.microsoft.com/)
2. In the navigation pane on the left, click mail flow. Then click connectors.
3. Click +
4. On the pop-up window that follows, select From: Office 365 and To: Partner organization. Then click Next
5. Under *Name:, enter Paubox. Make sure the checkbox labeled Turn it on is checked, then click Next
6. On the next screen, under When do you want to use this connector?, select Only when I have a transport rule set up that redirects messages to this connector, then click Next
7. Choose Route email through these smart hosts then click +
8. During setup, you'll be provided with the value to enter in the In the "add smart host" box
9. Enter the provided smarthost, then click Save
10. Click Next
11. On the next screen, make sure Always use Transport Layer Security (TLS) to secure the connection (recommended) and Any digital certificate, including self-signed certificates are selected. Click Next.
12. Click Next again
13. On the next screen, click the + and enter a test email address as the validator email address: pauboxtesting@gmail.com
    ... and then click Next.
14. Click Validate
15. After the test is successful, click Close
16. Next click Save
17. The Paubox connector for Microsoft 365 is now live.

Note: the validation may indicate failure even when successfully created.

Part II: Create a new rule

1. In the navigation pane on the left, click mail flow. Then click rules
2. Click the + and select Create a new rule…
3. On the pop-up window that follows, in the Name field enter Route to Paubox.
4. In the Apply this rule if section, select The Sender and domain is ... and enter in the domains to send via Paubox
5. In the Do the following section, select Redirect the message to and the following connector ... and select the Paubox connector
6. In the Except if section, select The recipient and is external/internal ... and select InOrganization
7. Click Next, on the following page click Next, followed by Finish. 
8. After saving, click on the newly created Transport Rule, and Enable the setting. (Wait 30 seconds for it to enable)

Congratulations! You have successfully used the Microsoft 365 Exchange Admin Panel to route email from selected domains to use Paubox encrypted email as their smart host gateway for outbound, HIPAA compliant email.