Spam-trigger words: which ones still matter in 2026

Email-marketing folklore is full of advice about banning certain words from subject lines and body copy. Most of it is outdated. Some of it still matters.

Here's where the data lands.

What still matters

A short list of patterns that genuinely correlate with worse deliverability in current scoring corpora:

• ALL CAPS in subject lines. Still a meaningful negative signal across major MBPs.
• Excessive exclamation points. More than 2 in a subject line, or more than 3 in a body, correlates with worse placement.
• Currency symbols stacked. "$$$ Make money fast $$$" pattern is fossilized and still tripped by spam filters.
• All-image emails. HTML emails with image-to-text ratios above ~70% are filtered harder than text-rich emails. Always include real text alongside images.
• Generic Viagra / lottery / mortgage trigger phrases. Still in the filter rules; if you're not writing pharmacy spam, you don't need to think about these.

What stopped mattering

Words that 2015-era guidance flagged that no longer move the needle:

• "Free" in the subject line. Used naturally ('Free shipping on orders over $50'), it's neutral.
• "Buy now" in CTAs. Standard marketing language; spam filters don't penalize it specifically.
• "Click here" as anchor text. Bad UX, not a deliverability problem.
• "100% guaranteed" in body. Filter rules updated; no longer a strong signal.
• "Limited time offer" by itself. Pattern-matching is now contextual, not keyword-based.

What matters more than words

The shift in spam filtering since ~2020 is that content keyword matching is a small part of the model. The dominant signals are:

• Sender reputation. Your domain's history with the recipient's mailbox provider.
• Recipient engagement. Whether your prior sends to this recipient got opens, clicks, replies.
• Authentication setup. SPF, DKIM, DMARC alignment.
• Volume patterns. Sudden spikes look like list-buying.
• List hygiene. High bounce rates and spam-trap hits damage reputation directly.

A sender with strong reputation can use the word 'free' a hundred times. A sender with poor reputation gets filtered on neutral content. The structural lever isn't word choice; it's reputation.

The audit worth running

If your sends are landing in spam at unusually high rates, the order of operations:

1. Check authentication. SPF, DKIM, DMARC. The single biggest cause of sudden deliverability drops is misconfigured authentication.
2. Check bounce rate. Should be under 2%. Above 5% is acute danger.
3. Check engagement. Are your recipients opening, clicking, replying? If engagement is collapsing, the filter follows.
4. Then check content. ALL CAPS, exclamation density, image-to-text ratio.

Most deliverability problems are not solved at the content layer. Spending hours rewriting copy when your DKIM is broken is the classic email-marketer mistake.

A useful exercise

Run your last 10 sends through this checklist:

• Subject line in mixed case (not ALL CAPS)?
• 0-1 exclamation points in subject?
• Image-to-text ratio under 60%?
• Real plain-text alternative in the multipart message?
• List-Unsubscribe header present?
• Authentication configured?

If all six are yes and you still have deliverability problems, the issue is reputation or list hygiene — not the content of any individual email.

What our tool does

Our deliverability lint flags content-level issues automatically — ALL CAPS, exclamation density, all-image bodies, missing unsubscribe links, suspicious-domain links in the body. But it also reminds you when content isn't the issue. If your domain reputation is poor, fixing the email won't fix the placement. We surface that explicitly so you don't waste hours on the wrong layer.

For a deeper read on deliverability mechanics, the deliverability section of our glossary has the definitions and links. And if you want to score your draft against the full rubric (spam, clarity, CTA, persuasion), try our editor — anonymous run, no signup.