An email was getting quarantined even the sender was whitelisted through office 365 rule

An email was getting quarantined even the sender was whitelisted through office 365 rule.

After looking into the header of the quarantined email found the "SFV:BLK" which means the sender was blocked by the recipient as per (Anti-spam message headers - Office 365 | Microsoft Docs).

So when to the effected user outlook and then 

on the Home tab, then "Junk Email Options" then "Blocked senders" tab, the quarantined email sender was added there. so after removing from there, next time the email was not quarantined and was successfully delivered.