Boxy 2 is the first major update to the powerful and minimal email client for Mac, powered by ‘Inbox by Gmail’. It features a redesigned interface, revamped multi-account and notification system, new themes and features, and tons of improvements.
It’s simple, easy to use, and allows you to organise all your emails quickly and efficiently.
I think i'l go back with Polymail because of the performances issues.
The only thing new I saw is the markdown feature which is nice.
However everything else it's the same... Just the regular app with custom CSS styles.