How to add a smart host in Office 365 Exchange online

In order for outbound email from Microsoft Office 365 to be routed through a smart host, we need to create a new send connector in Office365 and point it to your smart host.
Create a new send connector in Office 365

Log in to the **Office 365 Exchange Admin Center (EAC)**
Select the **Admin > Exchange**menu
Select the **Mail Flow > Connectors** menu. Then, select **Create a new Connector**
Set the mail flow scenario
- Select **Office 365** from the From: drop-down
- Select **Partner Organization** from the To: drop-down
Select **Next**
Enter a **name** and **description** for the connector. You may also select the checkbox to make the connector active immediately
Select **Next**
Select the **Only when email messages are sent to these domains** option
1. Select the plus (**+**) to add domains that should use this connector
2. Enter a value of * (asterisk).This is a wildcard that will route all outbound emails through your smart host
Select **Next**
Select the **Route email through these smart hosts** option
Select the plus (**+**) to add your smart host:_domain-com._outbound1-na.mailanyone.net
Click the **Save** button
Select **Next**
Select the checkbox for **Always use Transport Layer Security (TLS) to Secure the Connection (recommended)**
Select Issued by a trusted certificate authority (CA) from the list
Select **Next**
Add an email address of a recipient for a domain **external** to your organization, and select Validate to test

**Note:** If you did not choose to turn the connector on in Step 6, validation of the connector will fail. If your validation results show that the connection was successful, but the email failed to send because "The domain of the recipient is not configured as part of connector" - this may be due to the connector being disabled. Try enabling the connector and re-attempting the validation.

Once Office365 has been successfully validated, select **Save**
Update your SPF record accordingly