Why Deliverability Matters More Than Ever
In 2026, email providers are more aggressive than ever at filtering messages. Google and Yahoo's 2024 sender requirements have become the baseline, and new AI-powered spam filters can detect promotional patterns with unprecedented accuracy. If your emails aren't reaching the inbox, nothing else matters.
Email Authentication: The Foundation
SPF (Sender Policy Framework)
SPF tells receiving servers which IP addresses are authorized to send email on behalf of your domain. Without it, your emails are far more likely to be flagged as spam. Set up an SPF record in your DNS that includes your email service provider's sending IPs.
DKIM (DomainKeys Identified Mail)
DKIM adds a digital signature to your emails that proves they haven't been tampered with in transit. Most email platforms generate DKIM keys automatically — you just need to add the provided DNS records to your domain.
DMARC (Domain-based Message Authentication)
DMARC ties SPF and DKIM together and tells receiving servers what to do with messages that fail authentication. Start with a monitoring policy (p=none), review reports, then gradually move to quarantine (p=quarantine) and finally reject (p=reject).
IP Warm-Up
If you're sending from a new IP address or domain, you need to warm it up gradually. Start with your most engaged subscribers — those who regularly open and click. Send small volumes (50-100/day) and increase by 25-50% each day. Most warm-up periods take 2-4 weeks.
Content Best Practices
Avoid spam trigger words, maintain a healthy text-to-image ratio, and always include a clear unsubscribe link. Personalize subject lines and preview text. Test your emails with tools like Mail Tester or GlockApps before sending to your full list.
List Hygiene
Remove inactive subscribers regularly. A smaller, engaged list will always outperform a large, disengaged one. Set up automated re-engagement campaigns for subscribers who haven't opened in 90 days, and remove those who don't respond.
Monitoring & Tools
Use Google Postmaster Tools to monitor your domain reputation with Gmail. Set up DMARC reporting with a service like Valimail or dmarcian. Track your deliverability metrics (inbox placement rate, bounce rate, complaint rate) across all major providers.