OK just got in more test results.
It seems to be filtering certain URL's and not others. Ones that are blocked you can send if you do not have it hyperlinked or with the
www. in front of it. A blocked domain can be sent and will go through if its just xyz.com.
So if you leave off the www and don't make it hyperlinked the system is not blocking it. They also seem to be referencing a database as some adult keywords went through but others less extreme did not.