View mail messages in full screen

On Outlook on Mac, when I double-click on an email I received or compose a new email, it opens up as a modal window on the top of the maximised main window and I can't maximise the modal window.

Reading the above reply, it seems that it is the 'intended feature' and there is no way to enable a setting that will allow me to maximise the modal window or open emails (existing or new) on its own window. It this the correct understanding?

If NO: Then how do I open an emails or compose a new on its own window that I can maximise?

If YES: Then I must admit its a poorly designed 'intended feature'. Did Microsoft actually speak to real users before making this feature decision, I wonder!

Hi nikand. To open a message in its own window, Double-click a message in the message list. Double-click the title bar, or click the green button in the upper left of the window to maximize the window. Message windows can't go full-screen, although the main Mail window can. When you close a message window, Mail remembers its size and location. As long as you close a message window maximized, every subsequent message window will open maximized. You can also resize a window by clicking and dragging from the edges or corners of the window.

When you don't want to open a message in its own window, but would like more space for your message, you can click and drag the border between the message list and the message viewer left or right. To get even more space, you can hide/unhide the mailbox list by pressing the Command-Shift-M keys, or by clicking View from the menu bar and selecting "Hide Mailbox List".

Resources, some of which is also available from the Help menu in Mail's menu bar:

Mail (Yosemite): Mail overview

Mail (Yosemite): Read messages

Mac Basics: Use Mail on your Mac - Apple Support

https://www.apple.com/ca/support/osx/mail/

OS X Yosemite: Window basics

When you enter full-screen mode while in Mail, and Double-click a message to open in its own window, you get what you see in your screenshot. It's called a modal window or sheet and it can't be resized, only closed. However, if you want to keep the modal message window open and still access the main window, you can press the Command-Option-N keys to open a new main viewer window full-screen in a new space. Use the four finger swipe gesture left or right on your trackpad to move between the spaces.