If you have a sender who's e-mail to you continues to go to the junk folder. There is two ways you can whitelist the user's e-mail so outlook and proofpoint does not identify it as junk and allows the e-mail through.
1) Allow the sender in Outlook.
Right click on an e-mail in Outlook and select "Junk" and then click on "Never Block Sender"
2) In your proof point digest that is regularly e-mailed to your inbox, find an e-mail from the sender and select the "Allow Sender" option.
Additionally if you click on the "Manage My Account" option you can see quarantined messages and also manage your list of allowed senders.