This article explains how to set up a MailChannels smarthost relay in Microsoft Exchange 2016.

Step 1: Setup an Authenticated Smarthost Relay

1. Log in to the Exchange Admin Center (EAC) from the Exchange server itself using the URL https://localhost/ecp. You may also access your EAC from other browsers using the fully-qualified domain name (FQDN) of the Exchange server https://<ServerFQDN>/ecp
   
   
2. Choose Mail Flow and under this section, click on send connectors.
   
   
3. Click to add a new send connectors using the Add+ icon.
   
   
4. Name the send connector appropriately(MC in the below example) and select Internet from the "Type: " menu. This allows integration with an authenticated Smart Host and adds the required/default send permissions to route messages through an external host(outside of the domain forest).
   
   
5. Click on "Next".
   
   
6. Select the "Route through smart host" option.
   
   
7. Click to add a Smart Host using "Add+" icon
   
   
8. Enter smtp.mailchannels.net as the FQDN(Fully Qualified Domain Name) and click the Save button.
   
   
   
   
   
9. Click on "Next".
   
   
10. Select "Basic Authentication" and select the checkbox "Offer basic authentication only after starting TLS". 
    
    
11. Enter your MailChannels SMTP username and SMTP password in the Username and Password fields:
    
    
12. Click on "Next".
    
    
13. Click to add a new Address Space using the "ADD+" icon.
    
    
14. In the text box provided, enter an " * " as the FQDN(Fully Qualified Domain Name) and click "Save". 
    
    
    
    
15. Click on "Next".
    
    
16. Click the "ADD+" icon to add the "Source Server" associated with your new MailChannels send connector:
    
    
    
    
17. Click on "Finish".
    
    
18. Send a test message from an account on the Outlook 2016 server to ensure that your save configurations were correctly entered and that your MailChannels Smart Host send connector is configured and ready for live message traffic.

Fixing Common Issues

Step 1: Alternate SMTP Ports

MailChannels supports connections to alternative SMTP ports for Outbound Filtering. Smarthost relays can be configured to use ports 2525, 465 or 587 should 25 be inaccessible to you for any reason.