The Litmus blog had a good blog post earlier this month about mobile email and compatibility with a few things like image blocking, ALT text and more.
The chart below covers some popular email apps for mobile, and mobile email compatibility basics like support for media queries/responsive design, image blocking, preview text, alt text, and more. Inconsistencies are still bound to pop up, so be sure to test your email before you send.
Source: litmus.com
