
People enjoy using the standard Mac email application to easily send and receive emails. At the same time, the program can work in full-screen mode, and with the release of macOS High Sierra, support for automatic activation of Split View mode when a new email arrives.

If the full screen mode is active (for example, when you watch a video in Safari in full screen), when a new e-mail is received, the screen is automatically split in Split View mode. But this mode of operation is not always convenient and can be very distracting.
How to stop Mail from launching in Split View while watching a video on Mac
Fortunately for those who do not need to activate Split View in full screen mode, there is good news - you can turn off the automatic display of the secondary window by following these steps:
1. Open the Mail app and navigate to the menu bar.
2. Click on Mail → Settings.

3. Click the General tab.
Uncheck the "Open messages in Split View full screen" option.

After deactivating it, the Mail application will open a new message as a floating, superimposed window. Please note that this behavior only applies to the full screen view of the application (navigate with the green button). In normal Mail mode, new messages or replies are always created in a separate window on top of others.
See also:
- How to change the icon of an application, folder or file on Mac (macOS).
- How to automatically switch the language (layout) on the keyboard in macOS or Windows.
- КлавишиOption (Alt) Key Features on Mac (macOS), 20 Tips You May Not Know About.