If you are using an email for work then it is likely that you are using an Exchange or IMAP account. Exchange and the IMAP servers automatically archive your email so that it becomes possible for you to access it anywhere. In order to back up the message folders, you can move or delete older items with Auto Archive or export the items to a .pst file that you can restore later as needed and use by importing.
The most important data on the computer are the email and contacts. Backing up your Outlook data is very simple like copying a single file.
The following are the steps for backing up Microsoft Outlook-
Step 1: The first step is to Select File > Open & Export > Import/Export.
Step2: After selecting File select Export to a file, and then select next.
Step 3: After selecting “Next “Select Outlook Data File (.pst) and select next.
Step 4: After selecting “Next” select the mail folder you want to backup and select next.
Step 5: The next step is to choose a location and name for your backup file, and then select Finish
Step 6: After choosing the location if you want to make sure that no one has access to your files, enter and confirm a password, and then select OK.
Note: The messages which are kept in the .pst file are no different from other messages. You can forward, reply, or search through the stored messages as you do with other messages.