Why Are My Emails Going to Spam? 7 Causes and How to Fix Them

Email deliverability is one of those invisible problems. Your email client says "Sent." But the recipient never sees it — or finds it days later buried in spam. For small businesses, this is a genuine revenue problem: proposals, invoices, follow-ups, and onboarding emails are all silently failing.

The good news is that most spam issues come from a short list of fixable causes. Let's go through them.

1. Missing or broken SPF record

SPF (Sender Policy Framework) is a DNS record that tells receiving mail servers which servers are allowed to send email on behalf of your domain. If you don't have one — or if it's misconfigured — Gmail, Yahoo, and Outlook will treat your emails with suspicion.

The most common SPF mistake is having no record at all. The second most common is having multiple conflicting SPF records (you can only have one). The third is using soft-fail (~all) instead of hard-fail (-all), which tells receiving servers "this might be legitimate" rather than enforcing your policy.

2. No DKIM signature

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to every email you send. Receiving servers check this signature against a public key in your DNS to confirm the email actually came from you and wasn't tampered with in transit.

Without DKIM, your emails have no verifiable identity. Gmail and Yahoo now require DKIM for bulk senders, and even for lower-volume senders it's a strong ranking factor in spam filtering decisions.

3. No DMARC policy

DMARC (Domain-based Message Authentication, Reporting & Conformance) sits on top of SPF and DKIM. It tells receiving servers what to do when an email claims to be from your domain but fails authentication: ignore it, send it to spam, or reject it outright.

Without DMARC, there's no enforcement. Anyone can send email that appears to come from your domain — a tactic used in phishing attacks — and most mail servers will have no policy to act on. Gmail and Yahoo now require DMARC to be set for all senders.

4. Sending from a shared or low-reputation IP

When you send email through a provider like Mailchimp, Constant Contact, or a shared web hosting server, you share an IP address with thousands of other senders. If any of them have been flagged for spam, your emails inherit some of that bad reputation.

This is especially common with small business web hosting plans where transactional email (contact forms, order confirmations) goes through the same shared server IP as everyone else on the host.

5. High spam complaint rate

Every time someone clicks "Report spam" on one of your emails, Gmail records it. Google Postmaster Tools shows your domain-level complaint rate. If it exceeds 0.3%, Gmail will start routing more of your mail to spam automatically.

This is most common for marketing or newsletter emails, but it can affect any domain. A few angry recipients marking transactional emails as spam can tank your sender reputation quickly.

6. Sending from a mismatched or newly registered domain

Mail servers look at alignment: does the domain in the "From" address match the domain in your SPF or DKIM record? Misalignment is a spam signal. Similarly, brand-new domains have no sending history, so they start with low trust.

If you recently registered a new domain or rebranded, your email reputation effectively starts at zero. You'll need to build it up gradually by starting with low send volumes and scaling up over weeks.

7. Spammy content or missing unsubscribe link

Even with perfect authentication, the content of your email matters. Spam filters analyse subject lines, body text, link ratios, and HTML structure. Certain patterns trigger filters: excessive capitalisation, phrases like "FREE OFFER," deceptive subject lines, or a high ratio of images to text.

For bulk email (newsletters, promotional campaigns), CAN-SPAM and GDPR both legally require an unsubscribe mechanism. Missing it will get your emails flagged immediately.

Where to start

The first three causes — missing SPF, DKIM, and DMARC — are the most common and the most fixable. They don't require any technical expertise to implement once you have the right DNS values. The authentication problems are also entirely in your control, whereas sender reputation takes time to build.

The fastest way to find out which of these apply to your domain is to run a free audit.