Does it possible to know the emails that's rejected at the edge/perimeter of EOP(Defender for o365)?

[vinay2010]

Does it possible to know the emails that's rejected at the edge/perimeter of EOP(Defender for o365)?

As the email get rejected at edge level, does it possible to know from which sending IP emails got rejected in Defender for o365 portal ?

[#2]

Depends on which filter blocked it, but generally speaking no. Run a message trace based on sender/recipient details, if it's not visible therein, it's either blocked on the edge or never reached M365.

[#3]

@vinay2010 

Message trace can provide more insights