If you’re sending cold emails and they keep landing in spam, you’re not alone. Most people guess at what’ll get them into the inbox, then cross their fingers. There’s a better way. If you want real feedback and a fighting chance at actually reaching humans, this guide is for you.
You don’t need a PhD in email deliverability. You just need to know what matters, what doesn’t, and how to use tools like Mailgenius to stop shooting in the dark.
Why Cold Emails Get Sent to Spam (and What You Can Actually Control)
Before you start optimizing, let’s get real. No tool can guarantee every email lands in the inbox. But you can tip the odds in your favor by understanding what triggers spam filters—and what’s just marketing noise.
Here’s what actually matters:
- Your sending reputation — Are you a known spammer, or does your domain have a good track record?
- Technical setup — SPF, DKIM, DMARC. If these sound like alphabet soup, don’t worry, we’ll demystify them.
- Email content — Not just what you say, but how you say it (and how it’s formatted).
- List quality — Are you writing to real people, or blasting scraped addresses?
- Sending behavior — Are you acting like a human, or a robot?
The rest? Don’t lose sleep over the color of your CTA button or whether you used the word “free” once. Focus on what moves the needle.
Step 1: Get a Baseline—Test Your Email With Mailgenius
Before you fix anything, you need to know where you stand. That’s where Mailgenius comes in. It’s a spam checker that actually breaks down why your message might get flagged, not just if it does.
How to use Mailgenius:
- Go to the site and get your test email address.
- Mailgenius will give you a unique email address. Use this as your recipient.
- Send your cold email to that address.
- Send it exactly as you’d send it to a real prospect—same subject line, signature, links, everything.
- Check your Mailgenius report.
- After a moment, you’ll get a full breakdown of how your email performed—where it’d likely land (inbox or spam), and what’s helping or hurting you.
Pro tip: Run this test before you start making changes. It’s easier to see what actually works if you know your starting point.
Step 2: Fix Your Technical Setup (The Boring Stuff That Matters)
Most cold emails get tripped up by technical issues, not clever spam words. Here’s what Mailgenius will flag, and why you should care:
SPF, DKIM, and DMARC
- SPF: Proves your email is allowed to be sent from your domain.
- DKIM: Proves your email hasn’t been tampered with.
- DMARC: Tells inboxes what to do if SPF or DKIM fail.
If any of these are missing or misconfigured, you’re dead in the water. Mailgenius will call out exactly what’s wrong—usually in plain English.
How to fix it:
- If you’re using Gmail, Outlook, or a real business email provider, they’ll have instructions for setting these up. (Yes, it’s a pain. Do it anyway.)
- If you see red flags in Mailgenius, Google “set up [SPF/DKIM/DMARC] for [your provider]” and follow step-by-step.
- Wait a few hours after changes, then rerun the Mailgenius test.
Don’t skip this. You can write the world’s greatest email and still land in spam if your technical setup is broken.
Step 3: Clean Up Your Email Content
Now that your setup’s not sabotaging you, let’s look at your message. Here’s what actually matters (and what’s mostly myth):
What to Watch For
- Spam trigger words: Yes, a wall of “BUY NOW!!!” is bad. But most spam filters are smarter than that. A few common “salesy” words won’t kill you—unless your whole email reads like a bad infomercial.
- Weird formatting: Big, red, bold fonts, or a rainbow of colors? Don’t.
- Images: One small logo is fine. An email that’s just an image? Straight to spam.
- Links: Too many links or sketchy-looking URLs are a red flag. If you use a link shortener, expect trouble.
- Attachments: Avoid them in cold outreach. If you must send something, use a Google Drive or Dropbox link.
Mailgenius will highlight:
- Your text-to-image ratio
- Suspicious links
- Content patterns that look like spam
What’s mostly hype:
- Tiny tweaks like removing the word “free” or “guaranteed” won’t save a bad email.
- Emoji use is fine—unless you’re using 20 in a row.
Pro tip: If Mailgenius flags your email for something silly, use your judgment. Don’t rewrite your whole pitch for a single “maybe.”
Step 4: Check Your Sending Behavior
Even with a perfect setup and message, acting like a spammer can still get you filtered.
Here’s what to do:
- Warm up new domains: Don’t go from zero to a thousand emails a day. Start slow—send a handful of emails daily and ramp up over a few weeks.
- Don’t buy or scrape lists. Seriously. These addresses are often dead, fake, or spam traps. If you get flagged for high bounce rates, Mailgenius will let you know.
- Personalize, don’t blast. If you’re sending the same email to 500 people at once, it’ll look like spam—even if the content is decent.
- Monitor reply rates. The more genuine replies you get, the better your reputation. Mailgenius can’t track this, but it’s worth watching.
Mailgenius will sometimes detect patterns in your sending behavior, like sending too many emails too quickly. Pay attention.
Step 5: Rinse, Repeat, and Ignore the Noise
Getting into the inbox isn’t a one-and-done deal. Run your emails through Mailgenius every time you make a big change, or before starting a new campaign.
What to ignore:
- The latest “trick” or hack promising instant inbox access.
- Over-optimizing for every minor Mailgenius warning. Fix the big stuff first—setup, content, links.
- Anybody selling a “deliverability secret” for $999.
What actually works:
- Consistent, slow ramp-up of sending volume
- Clean technical setup (SPF, DKIM, DMARC)
- Human-sounding, relevant emails to real people
Quick Troubleshooting: Common Issues and What to Do
- SPF/DKIM/DMARC errors: Fix them in your DNS settings. Mailgenius will link to the failing record.
- High spam score: Rewrite your subject line, trim the links, and double-check formatting.
- Low engagement: Your content or targeting is off. No spam checker can fix that for you.
- Still in spam after fixing everything: Sometimes, it’s just bad luck or a burned domain. Try sending from a different domain, or wait a week and try again.
Final Thoughts: Keep It Simple, Iterate, and Don’t Chase Every Shiny Object
Cold email deliverability isn’t magic—it’s a mix of technical basics, common sense, and a little patience. Tools like Mailgenius take out the guesswork, but they’re not crystal balls. Fix what matters, ignore what doesn’t, and focus on reaching real people, not tricking spam filters.
Start small, test using Mailgenius, tweak, and don’t overthink it. The goal isn’t perfection. It’s just getting your message in front of someone who’ll actually read it. That’s enough.