You are unable to save a new Assessment in Phishing Readiness, despite populating all the necessary options.
Contains unauthorized target domains
Symantec Phishing Readiness
The target group contains recipients which are part of domains that are not provisioned in your Phishing Readiness instance.
Below you see that one of the recipient domains is an external domain (gmail.com). This will cause the error.
There are two ways to resolve this error.
1. Remove any recipients that are not part of provisioned domains from the target group.
2. Add the domain to the Phishing Readiness platform, if it belongs to your organization.
Refer to : Activate Additional Domains on Phishing Readiness