What You Need to Know
SPF Verification
Checks that the sending server is authorized by the domain's DNS records.
DKIM Signing
Cryptographically signs emails to prove they have not been altered in transit.
DMARC Policy
Defines how receivers should handle emails that fail SPF or DKIM checks.
Deliverability Impact
Properly authenticated emails are significantly less likely to be flagged as spam.
Email Authentication Checklist
Publish an SPF record listing all authorized sending servers
Generate DKIM keys and enable signing on your mail server
Start with a DMARC policy of p=none for monitoring
Review DMARC aggregate reports to identify authentication failures
Add include directives for third-party services that send on your behalf
Gradually move DMARC policy from none to quarantine to reject
Monitor authentication results after any email infrastructure changes
Ensure email signature tools do not break DKIM signatures
Frequently Asked Questions
Why is email authentication important?
Without authentication, anyone can send email claiming to be from your domain. Authentication protocols verify sender identity, protect your brand from impersonation, and improve email deliverability.
Do I need all three protocols (SPF, DKIM, DMARC)?
Yes. SPF and DKIM provide the verification mechanisms, while DMARC ties them together with a policy and reporting framework. All three are needed for comprehensive protection.
Will email authentication stop all spam?
No. Authentication verifies sender identity but does not evaluate email content. It prevents domain spoofing but not all forms of spam or phishing.
Does changing email signatures affect authentication?
Modifying emails after DKIM signing can invalidate the signature. Use a signature platform like Siggly that applies changes before authentication occurs.