Why Email Authentication Matters
Gmail and Yahoo now reject emails from domains without proper authentication. If you send business email without SPF, DKIM, and DMARC configured, your messages will either bounce or land in spam.
SPF (Sender Policy Framework)
SPF is a DNS TXT record that lists the mail servers authorised to send email on behalf of your domain. Example:
v=spf1 include:_spf.google.com ~all
This tells receiving servers: only Google's servers are allowed to send for this domain.
DKIM (DomainKeys Identified Mail)
DKIM adds a cryptographic signature to every outgoing email. The receiving server fetches your public key from DNS and verifies the signature — proving the email was not tampered with in transit.
DMARC (Domain-based Message Authentication)
DMARC ties SPF and DKIM together and tells receiving servers what to do if either check fails: nothing (p=none), quarantine (p=quarantine), or reject (p=reject). Start with p=none to monitor, then tighten over 4–6 weeks.
Testing Your Setup
Use mail-tester.com to send a test email and get a deliverability score. A correctly configured domain should score 9.5/10 or higher.