In order to restore all archived emails for any email id, follow the steps as mention bellow -

1. Install MailStore Desktop Client on a Window 7 / 8 /10 Desktop System. Download the Mailstore Client from the following link - https://win2012.diadem-tech.com/MailStoreClientSetup-13.2.0.20422.zip. After installing the above application, it will ask you for the server name e.g. - https://mailstore.diadem-tech.com/instance-name.
2. Login through the desktop client using the administrative credentials.
3. Once logged into MailStore with admin credentials, expand Other Archives on the left panel.
4. Right click on the intended user’s archive and chose Export to IMAP Mailbox.
   
   
5. Export IMAP Mailbox dialogue will appear. Provide the IMAP server and the intended user’s credentials and click Next button.
   
   
6. In the next screen, just click the finish button and the user’s emails will start to restore in IMAP folders.
7. You may also find older emails from MailVault in a separate IMAP folder.
8. If you do not require to restore all the emails for a user, you may also select emails for certain date range and restore them.