yep, that's my question. can I just create any .html file with html/css/pictures/links, and insert the code into an email using an email client (in my case, Apple's Mail.app on MacOS X Tiger 10.4), ...

Google is bringing AMP, its cut-down version of HTML, to email. Starting today, Gmail on the Web will be able to support embedded AMP content, with support rolling out to mobile clients later. Gmail ...