The current e-mail list in Proton Mail is very unintuitive for the eye and for the user interactions. It is one blend of text, since there is no differentiation of font weight or color.

There should be a clear differentiation in font weight or color between "from" and "subject" line. The Spark email app can be a great reference for that.

Spark also has an amazing feature, which is pinning important e-mails to the top of the list. This is such a game changer for e-mails that need follow-up, but I still want to see in my inbox list. Just pin them to the top until I unpin them.

Also it should be easier to move between emails with the keyboard (arrow keys should immediately change email in the preview, not only on hitting enter).

It should be possible to delete an email with the delete key (backspace on Mac).

It should be possible to select multiple emails from the list in order to delete them or move them to another folder.