If you use a third-party protection service or device to scan email before it's delivered to Microsoft 365, you can use a mail flow rule (also known as a transport rule) to bypass most spam filtering for incoming messages. For instructions, see Use mail flow rules to set the spam confidence level (SCL) in messages. Scanning for malware and high confidence phishing messages can't be skipped.
If you use a third-party protection service or device to scan email before it's delivered to Microsoft 365, you should also enable Enhanced Filtering for Connectors (also known as skip listing) so detection, reporting, and investigation features in Microsoft 365 are able to correctly identify messages sources. For more information, see Enhanced Filtering for Connectors.
If you need to bypass spam filtering for SecOps mailboxes or phishing simulations, don't use mail flow rules. For more information, see Configure the delivery of third-party phishing simulations to users and unfiltered messages to SecOps mailboxes.