Increase width of email newsletter

The width of content in email newsletters sent through Ghost is narrower than most other platforms.

This is due to Ghost adding 20px of border-spacing to the left and right sides, as well as setting a max-width of 600px.

I know 600px has historically been the width of emails, platforms like Gmail support a width of 630px. Also, most email platforms add their own margin to the sides of emails, so the additional 40px of border spacing seems unnecessary.

I’m curious on the logic behind the current width constraints.