Email Deliverability: Why Your Messages Land in Spam and the Fix

You wrote a clear email, sent it to 500 customers, and got near-zero opens. Before you blame the copy, check whether the message ever reached the inbox at all. Since early 2024, Google and Yahoo enforce sender rules that quietly route non-compliant mail to spam, and most small businesses we audit are tripping at least one of them without knowing. The good news is that deliverability is mostly a checklist of technical setup plus a few habits, not a dark art. Here is what filters your mail and how to fix each cause.

The three records that prove you are real

Mailbox providers will not trust mail from a domain that cannot prove it sent it. Three DNS records do that proving, and missing even one is the most common reason a small business lands in spam. They take an afternoon to set up and then run quietly forever.

• SPF: lists the servers allowed to send mail for your domain, so a receiver can reject forgeries
• DKIM: cryptographically signs each message so the receiver confirms it was not tampered with in transit
• DMARC: tells receivers what to do when SPF or DKIM fails, and since 2024 it is effectively required for bulk senders

Verify all three with a free DNS lookup tool before your next send. We have moved client open rates from 11 percent to over 30 percent with no copy changes at all, just by fixing a missing DKIM signature that had been silently dumping mail into spam for months.

The best subject line in the world cannot save an email the receiving server never trusted enough to deliver. Fix the plumbing first, then worry about the words.

Habits that wreck your sender reputation

Once the records are right, your behavior over time decides whether you stay in the inbox. Mailbox providers score your domain on a rolling reputation, and a few bad habits sink it fast. Sending from a free address like a gmail.com in the from field now fails authentication outright for bulk mail, so always send from your own domain.

The fastest way to ruin reputation is mailing a stale or purchased list. Hitting dead addresses and spam traps tells Google you are a spammer, and that judgment follows your domain. Clean your list: remove anyone who has not opened in 6 months, honor unsubscribes within a day, and never buy a list. Keep your spam-complaint rate under the 0.3 percent threshold the providers publish, because crossing it triggers filtering for everyone on the domain.

How to recover and stay out of spam

If you are already filtered, do not panic-blast your way out. Warm the domain back up by sending to your most engaged contacts first, the people who reliably open, so providers relearn that your mail is wanted. Add a real unsubscribe link, send at a steady cadence rather than in unpredictable bursts, and watch your metrics. Treat deliverability as ongoing hygiene, not a one-time fix, and your messages keep reaching the people who actually want them.

← Back to all articles