How to stop your emails going to spam
Short answer. Emails go to spam when the receiving server distrusts the sender: missing SPF, DKIM and DMARC records, a poor sender reputation, a stale list or content that reads like bulk mail. Fix authentication first, clean the list, warm the domain and send fewer, more relevant messages to people who expect them.
Updated 15 Oct 2026.
Why do emails go to spam?
Emails go to spam because the receiving mail server does not trust the message, the sender or both. Spam filters weigh four things: the content of the email (subject line, body text and attachments), the sender's reputation (the history of your domain and IP address), whether the domain is authenticated with SPF, DKIM and DMARC, and how past recipients behaved: opens, replies, deletes and spam reports.
The causes compound. A stale list produces bounces, bounces damage your reputation, and a damaged reputation makes every later send harder to deliver. That is why the fix is a sequence, not a single setting.
How do you set up email authentication?
Start here, because without authentication nothing else you do is believed. Three DNS records verify that you are who you claim to be:
- SPF (Sender Policy Framework) lists the servers allowed to send email for your domain, which prevents spoofing.
- DKIM (DomainKeys Identified Mail) adds a digital signature so the receiving server can confirm the message was not altered in transit.
- DMARC (Domain-based Message Authentication, Reporting and Conformance) builds on both and tells receiving servers what to do with mail that fails the checks.
All three are set once at the domain level. If you send through a sales engagement or email marketing tool, its documentation gives you the exact records to add.
How do you keep your email list clean?
Remove invalid, inactive and unengaged addresses regularly. Hard bounces and spam complaints are the two signals mailbox providers watch most closely, and both usually trace back to a bought or scraped list. In practice:
- Verify addresses before you send, not after they bounce.
- Purge contacts who have not opened, clicked or replied in a long time.
- Honour unsubscribe requests immediately and make the link easy to find.
- Use confirmed opt-in where people subscribe themselves, and never buy a list.
What sending practices protect your reputation?
Send from a custom domain, not a free webmail address. Keep your volume steady: sudden spikes look like a compromised account. Warm up a new domain or IP address by increasing volume gradually over weeks. Watch bounce and complaint rates as you go, and check the common blacklist services occasionally so a listing does not sit unnoticed.
Timing helps at the margin too. Send when your audience actually reads email, and keep a consistent schedule rather than bursts.
What content triggers spam filters?
All-caps subject lines, stacked exclamation marks and pushy promotional phrases such as buy now, limited time, act now and urgent. Heavy image-to-text ratios, broken links and unexpected attachments raise the same flags. Keep subject lines short, specific and honest about what the email contains, write mostly in plain text, personalise where you can and proofread: sloppy copy reads as low quality to filters and humans alike.
Why this works better on named accounts
Most deliverability trouble is self-inflicted by volume. A list of thousands of strangers forces you into the exact behaviours filters punish: bulk sends, template content, high bounce rates and low engagement. Working a named account list inverts every signal. You send fewer emails, each written for a known person at a company you chose, so replies rise and complaints fall away. Our lead generation page explains how we structure outreach around accounts rather than lists, and the Account-Based Marketing guide covers the wider approach.
Frequently asked questions
Why are my emails suddenly going to spam?
Something changed in one of the trust signals: an authentication record broke, your sending volume spiked, a campaign drew complaints, or your domain or IP address landed on a blacklist. Check SPF, DKIM and DMARC first, then your bounce and complaint rates, then the blacklist services.
Do SPF, DKIM and DMARC matter for small senders?
Yes. Major mailbox providers now expect authentication from every sender, whatever the volume. Without the records your mail is judged on content and reputation alone, and a new or small domain has little reputation to lean on. The records are set once and cost nothing.
How do I check my sender reputation?
Use the postmaster tools offered by the major mailbox providers and the independent reputation checkers. Watch your own numbers too: rising bounces, falling opens and any spam complaints warn you earlier than an external score will, and they point at the specific campaign that caused the damage.
Does cold email always go to spam?
No. Cold email that is authenticated, sent at a modest and steady volume from a warmed domain, and written individually for a named recipient is delivered like any other business email. It is bulk behaviour, not coldness, that spam filters punish.
Keep reading
- What is cold email? A step-by-step guide
- Follow-Up Email Sequence After No Reply
- Lead Generation vs Account-Based Selling
Want this run on your key accounts? Intandemly is an account-based selling company: the ABX platform and a consultant who work your named accounts with you. Talk to us