I'm not huge into email clients, but perhaps that's just because I never found one that offered me much that my web client does not. With that in mind, I sincerely wish you the best of luck and hope that you can change mind.
Unrelated, the CSS background on your marketing page is a little borked on larger screens:
I'm on a standard 27" apple display running at 2560 x 1440 (which was the default resolution).