Office 365 (Outlook 2016 for Windows) - Keyboard shortcuts
The keyboard shortcuts described in this article refer to the U.S. keyboard layout. The layout of the keys on other keyboards may not correspond exactly to the keys on a U.S. keyboard.
You can press the Esc key to close any open form or dialog box. However, if you do this, any information you add to the form or dialog box may not be saved.
See complete list of keyboard shortcuts:
Office 2016 for Windows