Email Deliverability: Why Your Newsletters End Up in Spam

You spent hours writing the perfect newsletter. You hit send. And 30% of your subscribers never see it because their email provider sent it straight to spam. Deliverability is the invisible problem that kills newsletter businesses.

What Deliverability Means

Email deliverability is the percentage of your emails that actually reach the recipient's inbox (not spam folder, not bounced, not silently dropped). Industry average is 80-85%. Good senders hit 95%+.

The Three Authentication Protocols

Email providers check three things to decide if your email is legitimate:

1. SPF (Sender Policy Framework)

SPF tells receiving servers which IP addresses are allowed to send email for your domain.

DNS TXT record for peaklight.ai:
v=spf1 include:amazonses.com ~all

This says: only Amazon SES is authorized to send email from peaklight.ai. Everything else should be treated with suspicion.

2. DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to every email. The receiving server verifies the signature against a public key in your DNS records. If the signature is valid, the email has not been tampered with in transit.

3. DMARC (Domain-based Message Authentication)

DMARC tells receiving servers what to do when SPF or DKIM checks fail:

DNS TXT record:
v=DMARC1; p=quarantine; rua=mailto:dmarc@peaklight.ai

This says: if authentication fails, quarantine the email (send to spam) and report it to me.

Beyond Authentication

Authentication gets you past the technical checks. But deliverability also depends on:

• Bounce rate: Keep it under 2%. Remove invalid addresses immediately.
• Complaint rate: Keep it under 0.1%. Make unsubscribe easy and obvious.
• Engagement: Email providers track opens and clicks. Low engagement signals spam.
• Content quality: Avoid spam trigger words, excessive links, and all-caps subjects.
• Sending volume: Ramp up slowly when using a new domain. Do not send 10,000 emails on day one.

The SES Advantage

Amazon SES has excellent deliverability because Amazon actively manages their IP reputation. They suspend senders with high bounce or complaint rates, which keeps the shared IP pools clean for everyone.

This strict enforcement is actually a feature. It forces you to maintain a clean list and good sending practices. The result is higher inbox placement rates than most self-managed email servers.

The Practical Checklist

Before sending your first newsletter:

1. Set up SPF, DKIM, and DMARC records in DNS
2. Verify your sending domain with your email provider
3. Add a visible unsubscribe link to every email
4. Process bounces immediately (remove hard bounces, retry soft bounces)
5. Start with a small list and ramp up volume gradually

See the AWS SES documentation for the complete setup guide.