As you might imagine, Google is determined to keep this secure. It reviews senders before they're allowed to send AMP-based email, and relatively few will support it out of the gate (including Twilio Sendgrid, Litmus and SparkPost).

You won't need Gmail to read these messages, at least. AMP emails will be readable through Outlook.com, Mail.ru and Yahoo Mail (owned by Engadget parent Verizon). If there's a major obstacle, it's that mobile Gmail support is still "coming soon." Like it or not, you'll have to leave the Gmail app on your phone if you want to interact with your emails.