Why Your Emails Land in Spam (and How to Fix It)

You can write the perfect email and it’ll do nothing if it never reaches the inbox. Email deliverability is the unsexy, technical, behind-the-scenes work that decides whether your campaign lands in front of your reader or quietly dies in their spam folder.

Most small businesses never look at deliverability until something breaks. By then, the damage is already done. Here is what actually drives it, the technical fixes most people miss, and how to dig yourself out if you’re already in trouble.

Why deliverability matters more than people realise

If 15% of your emails are landing in spam, you don’t have a 15% problem. You have a compounding problem. The people who don’t see your emails don’t engage. The lack of engagement tells filters your emails aren’t wanted. That increases the percentage that get filtered. Which reduces engagement further. And so on.

Bad email deliverability is a downward spiral. Good deliverability is the quiet foundation that lets everything else work.

The technical basics, in plain English

Three acronyms run the show: SPF, DKIM, and DMARC. They’re the email equivalent of ID checks: they let receiving servers verify that an email really came from who it claims to be from.

SPF (Sender Policy Framework). A record on your domain that lists which servers are allowed to send email on your behalf. If your email platform isn’t on that list, receiving servers get suspicious.
DKIM (DomainKeys Identified Mail). A cryptographic signature attached to every email you send. It proves the email wasn’t tampered with in transit and that it actually came from your domain.
DMARC (Domain-based Message Authentication, Reporting and Conformance). The policy that tells receiving servers what to do if SPF or DKIM fails. Most importantly, it reports back to you when something looks wrong.

If you don’t have all three set up correctly, your emails are getting filtered more than they should be. The good news: it’s a one-time setup, your email platform usually provides the exact records to add, and your hosting provider’s DNS panel is where you add them. Once it’s done, you don’t touch it again.

If you’re not sure whether yours are set up, free tools like MXToolbox can check your domain in 30 seconds.

Sender reputation: what builds it, what breaks it

Every domain that sends email builds up a reputation score over time. Receiving servers (Gmail, Outlook, Yahoo) use that score to decide whether your next email goes to the inbox or to spam.

What builds reputation:

Consistent sending volume (not zero one month, 50,000 the next)
Healthy engagement (opens, clicks, replies)
Low bounce rates
Low spam complaint rates
Real, opt-in subscribers

What breaks it:

Sending to bought or scraped lists
High bounce rates (more than 2% is a warning sign)
Spam complaints (anything above 0.1% is a problem)
Sending to people who never opted in
Wild changes in sending volume

The bounce problem

A bounce is an email that came back undelivered. Hard bounces (the address doesn’t exist) and soft bounces (temporary problems like a full inbox) both hurt your deliverability, especially in volume.

Most email platforms automatically remove hard bounces. But they don’t always clean inactive contacts whose addresses still technically exist but never open anything. Those quietly drag your reputation down over time.

Twice a year, prune subscribers who haven’t engaged in six months. Send them one “we miss you” re-engagement email first. If they don’t respond, remove them. Yes, your list shrinks. Yes, your deliverability improves.

The engagement problem

Gmail and the other big providers watch what your subscribers do with your emails. If lots of people open, click, and reply, you’re treated as wanted. If lots of people delete without opening, or mark you as spam, you’re treated as unwanted.

This is why list quality beats list size, every time. A small, engaged list builds reputation. A large, dead list destroys it.

The content problem (spam triggers)

Spam filters look at the content of your emails too. Common triggers:

Lots of money words (“free”, “guaranteed”, “act now”, “save big”)
ALL CAPS in the subject or body
Excessive exclamation marks
A high image-to-text ratio (especially emails that are basically one big image)
Shortened URLs (bit.ly and similar look suspicious)
Misleading subject lines that don’t match the content

None of these will single-handedly land you in spam if your reputation is otherwise good. But they stack up, and on a borderline campaign, they tip you over.

How to test where you stand

Before you send a campaign, run it through Mail-Tester (free, takes two minutes). It scores your email out of 10 and tells you exactly what’s hurting deliverability. Anything below 8 is worth fixing.

You should also send a test to a Gmail address, an Outlook address, and a Yahoo address you control. Check whether it lands in the inbox or in spam in each. If it’s landing in spam anywhere, something is up.

How to recover if you’re already in trouble

If your reputation has tanked, here’s the rough playbook:

Stop sending to anyone who hasn’t opened your last 10 emails. Get aggressive with this. Cut hard.
Reduce send volume by 50% for a month, while focusing only on your most engaged subscribers.
Improve content quality. Plain-text, personal-style emails rebuild reputation faster than designed campaigns.
Fix your SPF, DKIM, and DMARC if they’re not set up properly.
Be patient. Reputation takes weeks of clean sending to recover.

Most domains recover in two to three months of disciplined sending. It’s annoying, but it’s a fixable problem.

Need a hand?

Deliverability is the kind of thing that quietly costs you money for months before anyone notices. If you’d like a proper audit of your setup, or you suspect something’s wrong, see our email marketing service or get in touch.