Back in the day, the best website for answering the question “what CSS features does this email client support?” or probably more usefully “do most email clients support this particular CSS feature?” was Campaign Monitor’s CSS Support Guide for Email Clients. It’s still there and looks to still be a decent resource.

More recently we’ve got Can I email… by Rémi Parmentier which I’d argue is nicer. It’s modeled after Can I use… for web support features which is massively used by web developers to understand browser support.

With these things you can figure out what you can and can’t do. So you get to go through fun thought processes like:

1. Oh flexbox is pretty well supported actually!
2. And so are @media queries, wow!
3. Oh wait, none of the flexbox alignment or flow properties are supported, which kinda neuters how useful flexbox is, bummer.

There is a new one on the block as well: Email Client Feature Support Rankings. What’s neat about this is that it’s an alternate take: it’s not really about features, it’s about accessibility, performance, and internationalization. And then rather than re-do the actual testing, it’s more like a report card of who is doing well overall and who isn’t. The features themselves just link to Can I email…

The support situation on email is really wild, and has been forever. I’m sure it’s complicated, but why all email clients can’t use one of the three open source and extremely high quality browser rendering engines is beyond me.

I like the mission of the EMC:

The Email Markup Consortium (EMC) is a community-led group of industry professionals working to improve the email experience for everyone. Recipients should be able to easily access the content of every email sent to them, regardless of their device, email client, assistive technology or internet speed. The EMC collaborates with developers, creation and sending tools, and email clients to drive this vision forward at every step of the email journey.