https://arstechnica.com/gadgets/2019/03/google-brings-amp-to-email-turning-your-inbox-into-an-app/

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 will also be joined by Outlook.com, Yahoo Mail, and Mail.Ru, with their respective developers promising to add support soon.

AMP for email isn't just a warmed-over version of email with HTML formatting. The embedded AMP content will be able to offer features such as interactivity without having to click away from your inbox. For example, an online store could send you an email about a product or promotion you're likely to be interested in, and the AMP embed could allow scrolling through pictures of the products and even initiate the purchasing process. Or Pinterest could email you a selection of the day's popular items and you could pin them directly from your inbox.