The best way to contact support is via the Chat window in this support site or through the Dome9 Central Site
In the support site the chat window appear bottom right:
In Dome9 Central it appears at the bottom right ot needs to be opened under the messages item in the personal menu item:
Which will open the message window.
Few browsers Ad blocker or cookie settings will block the chat window.
Please make sure to white list Dome9 Central in the window doesn't show.
In Firefox, if custom settings for history are set, 3rd party Cookies must be enabled at least for visited sites (or always).
If none of the above works, email email@example.com or call 1-877-959-6889