Hi Ed,
A warm welcome to the forums.
White listing an addressee means that in general emails from that party will not be considered as spam, however that does not mean that emails containing suspicious links will be accepted.
That said the AI can generate false positives. I have seen examples where two URLs sent together give rise to a SPAM / Anti-Virus alert, but if sent separately do not.
To investigate what is going wrong, you will need to advise of the email subject, approximate date and time, sender's email address and ideally the rejection signature. Ideally you would not want to post some of the information here publicly, thus you need a staff member to catch this topic.
If you want to post the 6 URLs here, I can attempt to do some isolation testing.
Superusers are not staff, but they do have a direct line of communication into the business in order to raise issues, concerns and feedback from the community.
