When you click on the New Message button, the Composer window will appear in the bottom right corner of your browser. This is where you compose new email messages. 

In this support article, we show you how to resize the Composer window. For details on how to compose messages, please see Send Messages. 

Small Composer window

ProtonMail opens the small Composer window by default. This allows you to scroll through your entire inbox while continuing to compose your message.

Large Composer window

The large Composer window provides a greater working area, which is useful when composing longer messages. To Expand composer, click the 2-arrow icon in the top right of the Composer window (or use the keyboard shortcut Ctrl+Shift+M).

A larger Composer window will open, giving you more room to compose your message.

To Contract the composer, see the instructions for expanding it. 

Change the default Composer size

To change the default Composer window size, go to Settings ProtonMail Layout→ Composer and select Normal or Maximized.