Forum Discussion
O365 Exchange connectors apply spam filters before checking certificate
If you have devices like multifunction printers which need to send email the MS solution is to configure an inbound email connector. You can use source IP to identify the origen of incoming messages...
I believe yes, EOP applies IP reputation checks before evaluating inbound connector authentication (IP or certificate). Microsoft explicitly states that connectors cannot bypass anti-spam filtering, so dynamic or consumer ISP ranges listed in Spamhaus will be blocked even if you configure a TLS certificate or source IP.