February 2020 | SansSQL

Thursday, February 20, 2020

Disable Auto-Forwarding of e-Mails to external domain in Office 365

e-Mails are one of the most critical components and infrastructure of any business in the current day and age. e-Mails can bring in business as well as loss if misused. A lot of data theft can happens via e-Mails and it becomes most important to safegaurd the e-Mail infrastructure.
If a hacker gains access to a user's mailbox, they can auto-forward the user's email to an outside address and steal proprietary information.
One such step in safegaurding the data that leaks via emails is to disable the Auto-Forwarding of e-Mails to external domains.

To Disable Auto-Forwarding of e-Mails to External Domains in Office 365, Create a Transport Rule as below

  • From the Microsoft 365 admin center, Select Exchange --> Mail Flow --> Select the Rules tab --> Click on the plus sign and Choose "Create a new rule"
  • Name your new rule and Select More options
  • Click on the drop-down for "Apply this rule if", Select the "Recipient", and then "is external/internal"
  • Select "Outside the organization" and click OK
  • Click "add condition" and Click on the drop-down, Select "The message properties", then select "include the message type"
  • Open the select message type drop-down, choose "Auto-forward" and click OK.
  • Open the "Do the following" drop-down, select "Block the message", then choose "reject the message and include an explanation"
  • Enter the message text for your explanation that you want to show to your users, then select OK.
  • Scroll to the bottom and select Save
This newly created Transport Rule will now start blocking the Auto-Forwarding of e-Mails to external domains.