Sometimes when you’re composing a new email you need to look back at your inbox to gather up some additional info. Instead of dropping that email into drafts and closing it, OS X Daily points out that you can actually minimize the compose window in Apple’s Mail app.
All you need to do is tap the top of the email composition window and drag it down to the bottom of the screen. Your inbox is now fully available to you so you can double-check whatever other info you need to.
How to Minimize Emails in Mail App for iPhone | OS X Daily