The Mailbox app for iPhone streamlines email management, ... The check mark takes us to "All Mail", the icon in the far right is to compose a new email, and the top left pulls out all the features.

Whichever icon size you choose there will show up not just in the Finder’s sidebar, but in Mail’s as well. (Other sidebars, like the ones in iTunes, seem to ignore this setting.) ...

The Mail app usually shows right in the classic icon layout (Large icons/Small icons) in the Control Panel. But, if you cannot spot it, set the View by field to Category , and click on User Accounts .