Block Dropbox but allow download of sent links

Question

Hi All, 
 I have been given the task of trying to block uploads to Dropbox but allow users to be able to download sent links. 
 This is not an easy task as the Website and application uses port 443. If we use application control then this block the website too. 
 I can block the clients on the computers via GPO which leaves only users logging onto the website and uploading files. 
 I have noticed that generated links from Dropbox use the same start https://www.dropbox.com/s/****** but am waiting for Dropbox to confirm this. 
 If I was to do a Regex for https://www.dropbox.com/s/ (^https?://([A-Za-z0-9.-]*\.)?dropbox\.com/s/) to allow and another https://www.dropbox.com (^https?://([A-Za-z0-9.-]*\.)?dropbox\.com/) to block all other Dropbox will that allow links to be downloaded but block any other Dropbox sites? 
 Which list does it process first in the filter actions, block or allow? 
 Which list does it process first in the exceptions, block or allow? 
 Cheers 
 Isaac

sachingurung · Accepted Answer

Hi Issac, 
 Go to Web Filter Profile> Policies> Filter Action> websites. Here, add ^https?://([A-Za-z0-9.-]*\.)?dl-web\.dropbox\.com/ Regex in the block these websites option. Alongside add ^https?://([A-Za-z0-9.-]*\.)?cf\.dropboxstatic\.com/ and ^https?://([A-Za-z0-9.-]*\.)?bolt\.dropbox\.com/ int the allow these website option. 
 This configuration will block dropbox upload and download from the home screen but, if you open an existing file on the drop box and click on download button on the top right corner of the screen then the file will be passed. Note: Drop box application will be blocked. 
 Thanks