10.12 Sierra Mail not rendering some emails correctly I have Apple Mail and Airmail 3 running side by side. Emails from lists which used to be perfectly rendered are now rendered by Apple Mail as text, while still being correctly rendered by Airmail 3. What's up?

Example, rendered by Apple Mail:



And here's the same message rendered by Airmail 3:
This seems to be related to an image rendering bug in the new version of Apple Mail (Sierra).

When an &lt;img&gt; element in an HTML mail doesn't have both a "width" and a "height" attribute, the image is not displayed the first time the email is opened. If both attributes are defined, the image is properly displayed. If either one or both are missing, the image is not displayed.

The same &lt;img&gt; element is properly rendered in previous versions of Apple Mail.