Step 1: Sign into Exchange admin center.
Step 2: On the left pane, click More Features
Step 3: On the left pane, click on mail flow and select rules tab
Step 4: Click Add icon on the top-left
Step 5: Click Bypass spam filtering from the drop-down list
Step 6: Enter rule name in the Name area
Step 7: Select The sender’s domain name is from the Apply this rult if drop-down
Step 8: Click Save