Red Sift’s definitive guide to email security

Last updated: November 2025

TL;DR

This comprehensive guide covers email authentication protocols (SPF, DKIM, DMARC, MTA-STS) essential for protecting domains from spoofing and phishing in 2026.

Key takeaways:

• Email remains vulnerable: 3.4 billion phishing emails sent daily, with email being the primary attack vector for cybercriminals
• SPF and DKIM alone aren't enough: They authenticate senders but don't prevent exact domain impersonation
• DMARC is now mandatory: Required by Google, Yahoo, and Microsoft for bulk senders (5,000+ emails/day) as of 2024-2025, now standard in 2026
• Implementation timeline: Red Sift OnDMARC helps organizations reach p=reject enforcement in 6-8 weeks (fastest in industry)
• Business benefits: Stops phishing, protects brand reputation, improves deliverability, enables BIMI, supports compliance (NIS2, DORA, PCI DSS, GDPR)
• Technical challenges solved: Dynamic SPF eliminates the 10-lookup limit, automated tools accelerate troubleshooting
• MTA-STS adds transport security: Encrypts email in transit between mail servers

Bottom line: Email authentication has moved from optional to required in 2026. Organizations need DMARC at p=reject for complete protection, with modern platforms enabling rapid, safe implementation.

Email is a vital tool for the lifeblood of business communication all around the world. It’s so critical to the everyday running of organizations big and small, that many would agree it’s just as essential a service as electricity or water.

But its importance is exactly what makes email vulnerable from a cybersecurity perspective. In 2026, attackers continue to refine their methods. With 3.4 billion phishing emails sent every day, it's evident that email systems are the prime target for cybercriminals seeking access to your business. All it takes is a single employee  to fall victim to a socially engineered scam, click on an infected link, or download a malicious attachment, and your entire operation could grind to a halt.

Given how important it is for organizations to secure their email, we’ve developed this comprehensive guide to help both beginners and buyers with their email security related queries. In the following chapters, you’ll find in-depth information on:

• How attackers exploit weak gateways, misconfigured DNS records, and unmonitored domains
• Why SPF, DKIM, and DMARC work best together, and how MTA-STS strengthens transport security
• The buyer checklist: reporting depth, automation, policy enforcement, ROI, and time to value

Happy reading!