When sending email to a user on the Symantec Email Security.cloud service, the message is rejected. The sender receives a non-delivery email with a 500 series error code indicating that the recipient is invalid.
When the Address Registration feature is enabled, Symantec.cloud allows emails to be delivered only to valid email addresses.
If the recipient email address is not present in the Address Registration list, external emails sent to the address will be rejected with "550-Invalid recipient" error.
Either manually add the email address in the Symantec.cloud console, or perform an update using the Schemus Synchronization Tool.
Email addresses should automatically be added in Address Registration when at least one Outbound Email is sent from the email address of a registered domain .
Note: Once the changes have been committed, allow up to one hour for the changes to propagate across the Symantec.cloud infrastructure.