You spend hours crafting the perfect email, only for it to vanish into the “Promotions” tab or, worse, the dreaded Spam folder. If your open rates are tanking, it’s rarely because your subject line was “boring”—it’s usually because of technical email deliverability mistakes that trigger red flags for email providers. If you want to ensure your message actually reaches your audience, you need to move beyond just writing great copy. Here are five stealthy killers sabotaging your reach and how to fix them.
Most Email Service Providers (ESPs) use a generic tracking domain for your links. Because thousands of other senders—some of them low-quality—use that same domain, Gmail and Outlook might flag your email by association.
The Fix: Set up a Branded Tracking Link (Custom Tracking Domain). This ensures your links match your own domain, building "reputation equity" that belongs exclusively to you.While most people know about SPF and DKIM, DMARC is the final boss of email authentication. Without a DMARC record, major email providers have a harder time verifying your identity. In fact, these have become modern sender requirements for anyone sending to large lists.
The Fix: Add a DMARC record to your DNS settings. Even a simple "p=none" policy is better than nothing, as it signals to providers that you are monitoring your domain's security.Sending an email that is just one giant graphic is a major email deliverability mistake. Spammers often hide “trigger words” inside images to bypass text filters, so inbox providers are naturally suspicious of image-heavy layouts. Following Spamhaus best practices for content balance is essential to staying out of the filter.
The Golden Rule: Aim for a 60/40 ratio (60% text, 40% images). Pro Tip: Always include Alt-Text for your images. If the image doesn't load, the text tells the filter (and the user) what's supposed to be there.Keeping unengaged subscribers “just in case” they buy later is actually hurting your ability to reach your active fans. If email providers see that a large percentage of your list hasn’t opened an email in months, they assume your content is low-quality and will de-prioritize your delivery.
The Fix: Run a Sunset Policy. If someone hasn't engaged in 90–120 days, send one "break-up" email. If they don't click, remove them. A smaller, warmer list is far more profitable than a large, cold one.Spam bots send millions of emails in one hour and then go silent. If you send nothing for three weeks and then blast your entire list twice in two days, you are mimicking “spammy” behavior patterns.
The Fix: Maintain a predictable heartbeat. Whether it's once a week or three times a week, consistency helps filters recognize your sending volume as legitimate business activity.| Mistake Type | Impact on Deliverability | Ease of Fix |
|---|---|---|
| Technical (DMARC/SPF) | High (Instant Spam folder) | Easy (One-time setup) |
| Behavioral (Cadence) | Medium (Gradual decline) | Hard (Requires discipline) |
| List Health (Ghosts) | High (Damages domain rep) | Medium (Requires automation) |
While having a solid content strategy is essential for engagement, your best work won’t matter if these technical email deliverability mistakes keep you out of the inbox. By cleaning up your DNS records and maintaining a healthy list, you ensure that your hard work actually gets seen. Instead of guessing why your open rates are low, get a definitive answer in seconds.
Don’t wait for your next campaign to fail. Use our Inbox Placement Tool to run a live scan of your domain. We’ll show you exactly which filters you’re hitting and provide a step-by-step checklist to fix your authentication before you hit send.
