Postfix : How to accept mails based on Office 365 Tenant ID

Solution Verified - Updated -


  • How to configure postfix SMTP server to accept mails only with Office 0365 Tenant ID specified and reject all other mails.
  • The SMTP relay must only relay emails with a proper X-MS-Exchange-CrossTenant-Id: header and drop or reject anything else.


  • Red Hat Enterprise Linux 7

Subscriber exclusive content

A Red Hat subscription provides unlimited access to our knowledgebase, tools, and much more.

Current Customers and Partners

Log in for full access

Log In