Overview

• How to: Allow email from a named sender to come through without being quarantined
• Task: This article will help you set up your quarantine Allowed Senders

Instructions 

• Step 1] Login on the site https://security.microsoft.com/quarantine
• Step 2] Look for the Filter "Blocked Sender" and click on this if it currently displays "Don't show blocked senders"
  
  In the Filters list, scroll down to see "Show all senders" and select this option and Apply
  
  
   
• Step 3] Depending on the volume in quarantine, you may want to filter to find the email.  Use the martini glass with the cog to search for the sender:
  
  
  In the filters, enter the Sender address you want to see in the quarantine list.
  
  
   
• Step 4] Next, select the checkbox next to the message having the sender you want to add to your Safe Sender list
  Click on the "More" button, and click on Allow sender:
  
  
   

Outcome 

These steps will allow email from specified senders to bypass spam filtering and email going to quarantine.