Mail can't bypass spam filtering when the sender's IP is added to the Client Allow List

In Microsoft Exchange Online, you can add an IP address to the Client Allow List (based on the guidance in Configure the connection filter policy) so that email from that IP address assigned a Spam Confidence Level (SCL) rating of -1 and therefore not subject to spam filtering. However, in some circumstances, mail from that IP address is still filtered.

Administrators can use an Exchange transport rule to set the spam confidence level to Bypass Spam Score by using the Sender's IP address is in the range condition. For more information, refer to Use mail flow rules to set the spam confidence level (SCL) in messages.