How to unblock emails from one sender

Question

MS 365 has recently been blocking my emails from one particular sender. How do I allow the emails to be delivered.

Answer 1

Hi @DLPhoto

I would like to first confirm with you if this is your question:
You are using Exchange Online for email service.
Currently messages sent from one sender to your tenant get blocked, and you would like to receive these messages.

If I misunderstood it, please feel free to correct me.

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On sender side, did the sender receive any NDR messages?
If possible, please post the detailed information which indicates why these messages were rejected.

On recipient side, can you find the messages in the Microsoft 365 Defender portal?
Or in Message Trace?

You may follow the solutions in this link to whitelist the sender: Create safe sender lists in EOP
The most recommended method is to use a mail flow rule.

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