Hi @ Abin Ullas ,
You can refer to the following command to get the specified senders and rejected senders in all distribution groups, and export them as a csv for easy browsing:
Get-DistributionGroup | Select-Object Name, ManagedBy, AcceptMessagesOnlyFromSendersOrMembers, RejectMessagesFromSendersOrMembers | Export-Csv -Path c:\specifiedsenders.csv
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