Microsoft 365 DKIM setup
Microsoft 365 often requires a bit more explanation than simple hosted platforms because DKIM enablement depends on tenant-side activation and the right CNAME records.
What Microsoft 365 expects
For custom domains, Microsoft 365 usually expects two CNAME records tied to selectors before DKIM can be enabled for the domain in the admin side.
Typical setup process
- Add the custom domain.
- Publish the expected DKIM-related CNAME records.
- Wait for DNS to propagate.
- Enable DKIM for the domain within Microsoft 365.
Common pitfalls
- Publishing records at the wrong hostname
- Trying to enable DKIM before DNS is visible publicly
- Assuming SPF alone is enough for modern delivery
After enablement
Send a test message and inspect headers to confirm the expected domain is signing mail and that DMARC alignment works with the visible From domain.