Can't attach to webmail because adobe.tt.omtrdc.net is a "No content" site

This problem seemed to start with the update of Adobe Acrobat Reader DC to 074, but it could be related to a change apart from Reader DC.

Users now get an authentication failure when trying to Share pdfs as an attachment to gmail.  I've found the problem is that Reader DC is trying to connect to adobe.tt.omtrdc.net.  Our Untangle firewall uses zvelo.com to categorize sites in order to filter out undesired site categories.  Zvelo.com categorizes adobe.tt.omtrdc.net as a "No content" site, which the firewall blocks by default.  Simply adding the url to the list of allowed websites in the firewall isn't a good solution for us.  I believe I can create a rule to allow connections to the IP address for adobe.tt.omtrdc.net, but that address could change at any time.

I'm hoping Adobe can take a look at this, and perhaps find a solution or communicate with the powers that be at zvelo.com.  Nobody should have to create custom firewall rules for such widely used applications, or even have to make a special allowance for the site in a default firewall policy.