Archive email messages using Outlook 2011 and Outlook 2016

Introduction

There are two reasons to archive email messages: first, it allows messages to be accessed when the computer is not connected to the Internet, and second, it allows one to delete messages from the server — thereby reducing the total storage used that counts towards one’s remote storage quota — and still maintain a record of any archived messages.

Differentiate the folders which are online and which are locally stored

From the Outlook menu, select Preferences and go to the General option under Personal Settings.
Under Folder list, make sure there is no check mark next to Hide On My Computer folders.
Close the window.

Create a folder under On My Computer

While holding down the Control key, click on On My Computer.
From the menu that appears, select New Folder and type in a meaningful name such as Saved Messages.

Copy messages to the Saved Messages folder under On My Computer

Select the messages you need to be saved. You may select multiple messages by holding down the Command Key/Apple Key and clicking on the messages to be saved. Optionally, you can select a number of consecutive messages by clicking on the first message, pressing and holding the Shift key, and then clicking on the last message.
From the Message menu select Move → Copy to Folder.
In the Search box, type in the folder you created (e.g. Saved Messages).
This will display the folders which match that name. Make sure you select: On My Computer/Saved Messages.
Click Copy.
When the copying is finished, select the Saved Messages folder under On My Computer and confirm all the messages have been successfully copied. If you need to free up space, you can now delete the original messages from the server folder.