This issue wasted an hour of my life 
Recently users visiting google mail via the bluecoat proxy started complaining of popups which said…
Your request is being scanned for security purposes
Instead of “botching” it on the blue coat I offered my users a work around… something that they should be doing anyway… switch on encryption…. So within gmail -> settings -> general, tick the box…
This did the trick, my users mail is now more confidential than it was before and there were no more pop-ups 