Mail AssureMicrosoft 365 Header Based Configuration

Last Modified

Sun Apr 12 22:46 GMT 2020

Description

  • Looking to configure Microsoft 365 with Mail Assure
  • IP based restrictions is not ideal as IP addresses can only be added one at a time
  • Looking to use header based restrictions

Environment

  • Mail Assure
  • Microsoft 365

Solution

  • To restrict deliveries to your Office365 server(s) using Header based restrictions, use the Mail-flow rules to reject messages that do not have your SpamExperts headers
  • For header based rejections, you will need to set two rules:
    • Rule 1:
      1. Select Admin and choose Exchange from the menu
      2. Select Mail Flow
      3. Under Rules, click the +button and choose Create New Rule
      4. Add a Name for your Rule
        • For example: "Disable SpamFiltering and accept from SpamExperts"
      5. Select More Options
      6. Create Rule "A message header includes "X-Recommended-Action" header includes >> "accept"
      7. Select the + option
      8. Select OK
      9. In the "Do the following" part, select "Modify the message properties" >> "Set the spam confidence level (SCL)" >> "Specify SCL" >> "Bypass spam filtering"
      10. Select OK
      11. Enable Enforce from the rule mode
      12. Check the Stop processing more rules box
      13. Select Save
    • Rule 2:
      1. Select Admin and choose Exchange from the menu
      2. Select Mail Flow
      3. Under Rules, click the +button and choose Create New Rule
      4. Add a Name for your Rule
        • For example: "Reject Direct Deliveries"
      5. Create Rule "[Apply to all messages]"
      6. In the "Do the following" part, select "Reject the message with the explanation" and add something along the lines of "Did not deliver via Antispam Provider"
      7. Enable Enforce from the rule mode
      8. Select Save
  • Once setup correctly, you need to make sure the rules are in the correct order
  • Messages that are now delivered directly and not via the filtering nodes will be rejected with:
    • 550 5.7.1 TRANSPORT.RULES.RejectMessage; the message was rejected by organization policy
  • For more information on this, please go here