You spent hours writing the perfect newsletter. Open rate: 4%. Spam folder rate: probably 60%. Here’s why — and the technical fixes that actually move the needle.
The Three Things Inbox Providers Check
- Authentication — Are you who you claim to be? (SPF, DKIM, DMARC)
- Reputation — Do other people open and engage with your emails?
- Content — Does your message look like spam?
Set Up SPF, DKIM, and DMARC (Today)
This is the #1 fix and the one most senders skip. Without these three DNS records, Gmail and Outlook will be suspicious of every email you send.
- SPF — Says “these servers are allowed to send email for my domain”
- DKIM — Cryptographically signs your emails so they can’t be forged
- DMARC — Tells receivers what to do if SPF or DKIM fails
Build Reputation Slowly
Don’t blast 50,000 contacts on day one with a brand new sending domain. Warm up: start with your most engaged 500 subscribers, then expand the list gradually over 4-6 weeks.
Content Mistakes That Trigger Spam Filters
- ALL CAPS in the subject line
- Excessive use of “FREE”, “GUARANTEED”, “LIMITED TIME”
- One giant image with no text
- Lots of links shortened with bit.ly
- Missing physical mailing address (legally required by CAN-SPAM)
Test Before You Send
Tools like Mail-Tester.com give you a deliverability score and pinpoint exactly what’s wrong. Aim for 9+/10 before sending to your real list.
Hosting Matters Too
If you send transactional emails directly from your website, your host’s IP reputation affects deliverability. Premium hosts like Hostinger Cloud and ChemiCloud have clean IP ranges; cheap shared hosts often share IPs with spammers.
