To successfully whitelist our phishing emails when using MessageLabs or Symantec.cloud, you should add our IP addresses to a global Approved Senders list. This will allow our phishing emails through.
To add a global Approved Sender:
This new policy will allow any inbound mail flow originating from our IPs to reach your users. Be sure that all of our sending IPs are added to this list.
Note: Symantec does not recommend sending phishing tests through the Email Security.cloud infrastructure. They recommend sending phishing tests directly to the receiving mail server to avoid having our simulated phishing emails blocked or creating false clicks on your phishing messages. You may want to consider smart hosting, for more information on Symantec's position, please see their article on Phishing Assessment tests and Email Security.cloud.