By default, Outlook keeps a message window open after you respond to or forward that message, meaning you have to by hand it when you’re done. You can alter that so that Outlook immediately closes the initial message window as quickly as you hit the “Send” button. Here’s how.

Start by clicking the “File” menu on Outlook’s Ribbon.

On the sidebar that opens, click the “Options” command.

In the Outlook Options window that opens, change to the “Mail” classification on the left.

On the right, scroll down to the “Replies and Forwards” section, make it possible for the “Close original message window when replying or forwarding” option, and then click “OKAY” to save your settings.

That’s all there is to it. Now, your original message will close automatically as soon as you respond to or forward it.