Unable to Relay error on outbound email
All outbound emails are authenticated in one of two ways:
- Server based
- User based.
If you get the error
<server>.scanscope.net #550 Unable to relay it means that authentication has not been configured. Below are the authentication methods used.
- By IP address (Server Based)
The external IP addresses of your sending servers must be added to the Email Security product.
Navigate to the Email Security product, then Product Configuration menu and then Outbound Mail. Ensure that you add each external IP address to the list.
For Office 365, an SPF record is added to the Outbound Mail hosts. The following requirements must be met otherwise the message will be rejected.
- The IP address comes from an Office 365 server listed in the SPF record.
from:in the headers comes from a domain that is configured for the customer in the Domains section.
- SMTP Authentication (User Based)
For situations where the user is connecting directly from a dynamic IP address, SMTP authentication can be used with a username and password.