This is a limitation of the web viewer within Act! We use a control within the program which allows for basic browsing, but doesn't have the ability to open websites in anything beyond a basic form. As an avid G-Mail user I can tell you that I have seen no issues with functionality even though this message appears. If you do find something that isn't working right, let me know here so I can check on that, and see if there is a workaround.
