Stop spending queue slots and reputation on addresses Microsoft won't reliably deliver to

⚠ Read this before you change anything

Everything in this guide is an illustrative example, not a tested, certified, or supported configuration for your mail server, OS, version, or environment. Rejecting or filtering mail to or from a major share of consumer addresses has real trade-offs for your users, your correspondents, and — if you get the syntax wrong — your entire mail flow.

You are solely responsible for reviewing, testing, and validating any change before it touches a production system, for confirming it's compatible with your existing configuration and policies, and for any legal, contractual, or regulatory obligations that apply to your organisation's handling of email.

By copying, adapting, or deploying any snippet, script, or configuration from this guide, you accept full responsibility for the consequences — including but not limited to lost or delayed mail, service outages, and downstream impact on your users. DumpMicrosoft and its authors accept none. If you are not able or willing to take that responsibility, do not apply any of the changes described in this guide.