The "Destination not allowed" status of a message means that the destination is not enabled or allowed for that account. It can be caused by two reasons:

  • The account has the country filter configured in the Account Preferences. In this case it would be sufficient to add the country to the list of allowed destinations.

It is a destination country with a special regulation that requires previous steps or registrations. See Which destinations or countries have restrictions or require pre-registration or contact support.