How to disable the Microsoft 365 spam filtering
An admin login to the customer Microsoft 365 portal
Log in to M365 using the customer GA credentials.
Click into the Exchange admin centre in the left menu (you may need to click to Show All)
In the left menu, click into Mail Flow, Rules.
Click Add a rule and choose Bypass spam filtering
Give the rule a name, and then in the 'Apply this rule if' pull down choose
And choose Outside the organisation
Click Next, and Next again to accept the next screen settings.
The rule details in the right pane should now read
Click Finish, then click Done.