#Email Authentication

Your email spam score is a number assigned by spam filters — primarily SpamAssassin — that determines inbox vs. junk folder placement. Below 5 is safe; above 10 means blocked. This guide covers how spam scores are calculated, how to check yours free, and 10 concrete fixes: SPF/DKIM setup, list cleaning, content fixes, and blacklist removal.

Setting up SPF, DKIM, and DMARC is the single most important thing you can do to protect your sending domain and stay out of spam folders. I've set these up for hundreds of domains and it's rarely as complicated as people think — but the mistakes can tank your deliverability for months. This guide covers the exact DNS records you need, common pitfalls I see every week, and how to verify everything is working correctly using free tools.

Email deliverability determines whether your emails land in the inbox or spam. In 2026, the average deliverability rate is 85% — meaning 1 in 6 emails is never seen. This guide covers authentication, sender reputation, list hygiene, and tools to diagnose and fix every common deliverability problem.