Panel App

I wouldn’t even think this would be handy on a mobile phone.
It’s very basic and not intuitive at all. But, I guess that’s the free part.
What disappointed me more was the add-on’s didn’t even make sense for me.
Since I only use Gmail, it make sense to use the browser or the email client included in the mac os.

T4HJPalmer about MailTab for Gmail - Email Client