Email open to full screen. How to minimize window?

EclecticJen wrote:

Please let this be an obvious fix. On opening, each email displays in full screen. How can I minimize this window and make it a default?

That if this what the red/yellow/green pill buttons can do—exit full screen

individual email— same deal...Enter/Exit

Mail User Guide for Mac - Apple Support

Use apps in full screen on Mac - Apple Support

EclecticJen wrote:

Thank you for your response. It doesn't quite work for me. When tiled to the left or right I see the preferred size in email windows. When clicked it goes to a window taking the entire desktop with the only option in the 3 buttons at the top is to go to full screen. Both are annoying. Can this be changed? If so, where?

Un-tile the window and compare your results.

ref:

Use two Mac apps side by side in Split View - Apple Support