Log into Exchange Administration Center:

1. Navigate to Mail Flow
2. Select Send Connectors
3. Add a new connector (click the + sign)
4. Add a relevant name for this connector, Eg: SpamWeederOutFilter
5. Select : Internet (For example, to send internet mail)and click Next
6. Select Route mail through smart hosts
7. Add the SMARTHOST by clicking on the + sign
8. Click Save
9. Click Next
10. If you are using an IP outgoing user leave None / If you are using an Authenticating user select Basic Authentication > Input the Outgoing User and Password
11. Click Next
12. *Address space: > Click the + sign and in the *Full Qualified Domain Name (FQDN): input *
13. Click Save and Next
14. *Source server: - Click on the + sign and select the server from the list
15. Click OK and Finish

You need to ensure that the port 587 is being used:

1. Open the Exchange Management Shell
2. Run the following:

Set-SendConnector -identity "NAME OF CONNECTOR" -Port:587