The link provided by you was not under the category of web-base email. I have submitted the link to be considered by our internal team as web-based email. This Url was being considered as a non categorized URL by the appliance, If you have the action set to monitor for these kinds of URLS on the policy then your users will be able to go to this URL.
Since i have already submitted the URL to our team, The change should take affect on Monday. Kindly check back on Monday and if you still see the issue happening please open a TAC case.
In the future you can also submit such uncategorized URLS using the tool below(Please login using your CCO id: