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How to setup DKIM

In Microsoft O365

  1. Go to Security Center: https://security.microsoft.com
  2. Click Policies & Rules from the menu
  3. Click Threat policies
  4. Click Rules > DKIM
  5. Click domain you want to secure
  6. Click Create DKIM keys

Wait while Microsoft creates the private keys for the domain.

Copy DNS information, it's going to look like this: Hostname: selector1._domainkey and Value: selector1-<DOMAIN>-is._domainkey.<COMPANY>.onmicrosoft.com Hostname: selector2._domainkey and Value: selector2-<DOMAIN>-is._domainkey.<COMPANY>.onmicrosoft.com

Then create this CNAME record in your DNS.

Now, go back to DKIM page in Security Center. 1. Click the domain you want to secure 2. Enable: Sign messages for this domain with DKIM signatures

You might get an error because Microsoft cannot see the DNS record right away. This usually takes up to an hour to work. But might take days, so plan accordingly.