Importing a .pst file can help you restore Outlook data from a backup, transfer your data to a new computer, or merge your data from different accounts to your Mail account. To import a .pst file to Mail, follow these steps:
1. Open Mail and click on the 'File' tab.
2. Click on 'Import'.
3. Select 'Outlook Data File'
4. Browse to the file you want, and click 'Open'.
Note: A .pst file is a backup file that contains your Outlook email, contacts, and calendar. Outlook copies your email to the .pst file, including any attachments. When you import a .pst file, you will see your attachments as well.
Outlook does not copy some information to the .pst file, such as folder settings, message rules, and blocked senders lists. Therefore, these information will not be imported either.
Importing a .pst file does not affect your original data in Outlook. You can still access your email, contacts, and calendar in Outlook as usual.