Steps to Set Up a Mail Flow Rule to Bypass Spam Filtering in Microsoft 365:

1. Create a new mail flow rule in your Microsoft 365 Exchange Admin Center. 
2. Navigate to Mail Flow > Rules.
3. Click Add a rule, and give the rule a name, e.g. Spam Bypass.
4. Configure the Rule conditions:
   • Under 'Apply this rule if', select The sender > IP address is in any of these ranges or exactly matches.
   • Enter the appropriate IPs for your tenant, which can be found in the following article: MetaCompliance Mail Server IP Addresses - All Data Centres
5. Set the options by navigating to Modify the message properties > Select Set Spam Confidence Level (SCL).
   • Then, specify the SCL by selecting Bypass Spam Filtering (which sets this to: -1).
6. Then, save the mail flow rule.

See example below: