Email Authentication
Email authentication is a set of protocols (SPF, DKIM, DMARC) that verify the sender's identity and ensure emails haven't been forged or tampered with.
What Is Email Authentication?
Email authentication works in layers. SPF verifies that the sending server is authorised by the domain owner. DKIM adds a cryptographic signature proving the email content hasn't been modified. DMARC ties SPF and DKIM together with a policy telling receiving servers how to handle authentication failures. Together, these three protocols form a comprehensive system that protects both senders and recipients from phishing, spoofing, and spam. Modern email providers increasingly require all three for reliable inbox delivery.
Why It Matters for Newsletters
Email authentication is no longer optional. Google, Yahoo, and Microsoft now require proper authentication for bulk senders. Without it, your newsletters are far more likely to land in spam folders, and your domain is vulnerable to being impersonated by bad actors. Proper authentication is the foundation of everything else in email deliverability.
Best Practices
- Implement all three protocols: SPF, DKIM, and DMARC
- Test your authentication setup with tools like mail-tester.com
- Monitor DMARC reports to catch unauthorised use of your domain
- Keep authentication records updated when changing email service providers
- Document your authentication setup so it's easy to maintain
How Aldus Handles This
Aldus handles email authentication end-to-end. When you add a custom sending domain, the platform generates all required DNS records (SPF, DKIM) and verifies they're correctly configured before sending any email from your domain.