Email Deliverability 101: Why Your Emails Land in Spam
You have spent hours crafting the perfect email campaign. The subject line is compelling. The copy is tight. And then the results come in: 18% open rate, way down from last month. Chances are, a significant portion of your emails did not reach the inbox at all.
What is email deliverability?
Deliverability is the percentage of your emails that successfully reach the inbox rather than the spam folder or being blocked entirely.
The three pillars of deliverability
1. Technical infrastructure
- SPF - a DNS record that lists which servers are authorised to send from your domain
- DKIM - a cryptographic signature that proves the email was not tampered with
- DMARC - a policy that tells ISPs what to do when SPF or DKIM fails
2. Sender reputation
Your IP address and domain each have a reputation score maintained by ISPs. This score is based on bounce rate, spam complaint rate, engagement rate, and history of spam trap hits.
3. Content and engagement
Modern spam filters use machine learning. They look at subject line patterns, image-to-text ratio, link reputation, and whether recipients engage with your emails.
The list hygiene connection
Every invalid address you send to generates a hard bounce. Every abandoned address may have been repurposed as a spam trap. A list verification pass removes hard bounce sources, spam trap risks, disposable addresses, and role addresses.
The 30-day recovery plan
- Verify and clean your entire list
- Suppress all hard bounces and complainers immediately
- Confirm your SPF, DKIM, and DMARC are correctly configured
- Send to your most engaged segment only for 2-3 weeks
- Gradually re-warm your IP/domain by increasing volume 10-20% per week
