Update quarantine-faq.yml

@chrisda

Author: faoquong

defender-office-365/quarantine-faq.yml

@@ -224,6 +224,8 @@ sections:
       - question: |
           Why aren't users receiving notifications about their quarantined messages?
         answer: |
+           Firstly, confirm that the Quarantine notifications have not been recieved by leveraing message trace to run check. In message trace input the default sender address of [email protected] (or the custom sender address configured) and the recipient address of the user you are trying to run the check for. if confirmed that it is not generated then proceed to the next guidance below
+           
           If the quarantine policy that's defined for the [supported quarantine action](quarantine-policies.md#step-2-assign-a-quarantine-policy-to-supported-features) doesn't have notifications turned on, the quarantine notifications aren't sent.
 
           For more information, see the last table in [Anatomy of a quarantine policy](quarantine-policies.md#anatomy-of-a-quarantine-policy) and the individual feature tables in [Recommended settings for EOP and Microsoft Defender for Office 365](recommended-settings-for-eop-and-office365.md) to see which default quarantine policies have quarantine notifications turned on.