I make HTML-template (or signature only) for email (mobile-frendly) from PSD, PDF, other HTML. It maybe send with Thunderbird(Stationery) , Mailchimp , Campaing Monitor, Constant Contact , Stampready. I test my work in MSOutlook2007/2010/2013/2016 , Live Mail, Mac (OSX), outlook(livemail, not office 365), aol, yahoo, Android (Nexus7, Nexus6 and Nexus5), iPad, iPhone 5/6/6+ (native mail and Gmail_app).
100% hand code , purely and carefully.