How to Check Microsoft 365 DNS

Microsoft 365 leaves distinctive DNS patterns, but the cleanest way to judge the setup is to compare several record types together. MX, autodiscover, SPF, DKIM, and DMARC all add useful evidence.

This is especially helpful during migrations, audits, or when you need to confirm whether Microsoft 365 is the live provider rather than only one part of a mixed environment.

• Email Provider Setup Checker
• How to tell which email provider a domain uses

The MX hostname often shows Exchange Online Protection directly, and autodiscover usually points to Outlook service endpoints. Together, these are strong signals that Microsoft 365 is handling core mail functions.

If old MX records or broken autodiscover targets are still present, the domain may be only partly migrated.

• MX Lookup
• DNS records required for Microsoft 365

A domain can route mail through Microsoft 365 and still have weak or incomplete authentication. Check whether SPF includes Microsoft 365, whether the DKIM selectors resolve and signing is active, and whether DMARC is published.

Looking at these together makes it easier to tell whether the environment is clean or only mostly migrated.

• Email Security Check
• Microsoft 365 SPF, DKIM, and DMARC Setup

• Legacy MX records still sit alongside Microsoft 365
• SPF still authorises an old provider without a clear reason
• Autodiscover is missing or points somewhere unexpected
• DKIM is published but not enabled, or still points to old selectors

These are the sorts of problems that often explain why a domain looks partly correct in DNS but still behaves inconsistently in production.

• Check MX and autodiscover to confirm Microsoft 365 patterns
• Review SPF, DKIM, and DMARC together
• Look for old providers or stale migration leftovers
• Inspect a real message header if mail is failing or being filtered
• Compare the observed setup with the intended Microsoft 365 design

If you want to validate this topic in practice, these DNS Pro tools are the fastest next step.

• Email Provider Setup Checker
• Email Security Check
• MX Lookup