WEBP images are supported by every email browser these days, so you’d have assumed everything was good for email as well. Er - no. For a start, Google’s Gmail doesn’t support Google’s WEBP format properly, and turns them into JPEG. That’s fine, but it does mean that a WEBP with a transparent background won’t work very well. But, more to the point, any user on Microsoft Outlook on Windows - and there are a lot of those - will just see a broken image, because, in a refrain familiar ...
