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Outlook sender requirements
Reviewed by the Free Domain Mail editorial team · Updated
Outlook and Microsoft 365 recipients benefit from the same consistent authentication, list hygiene and predictable sending practices.
Authentication baseline
Publish SPF, DKIM and DMARC, then make sure the visible From domain aligns with a passing authentication result.
Use a real reply address and make it easy for recipients to understand who is contacting them.
Keep volume predictable
Increase sending carefully and avoid unexpected spikes.
Remove permanently failing recipients and investigate complaints before continuing.
Common mistakes to avoid
- Changing DNS records without validating them.
- Sending promotional messages to people who did not request them.
- Hiding the sender identity or reply path.
Frequently asked questions
Are Outlook requirements different from Gmail?
The exact filtering systems differ, but the core authentication and recipient-expectation principles are shared.
Can an MX record improve sending reputation?
MX mainly controls incoming mail. Sender authentication and behaviour affect outbound delivery.
Technical references
Primary specifications and provider documentation relevant to this guide: