Tip 1 of 5: Coming in El Capitan: iOS Mail features coming to Mac

Mail is getting a big update in El Capitan with many features reminiscent of the iOS version of Mail.
For example, if you are composing an email and want to check another message you can minimize the email you are drafting so that it goes to the bottom of the screen (similar to the way it works on iOS 8). This way you can access your email inbox and find the other message that you want to refer to.