Spam Trigger Words Are Mostly a Myth. Here's What Actually Gets Filtered
Search for "spam trigger words" and you'll find lists of 400 words to avoid. Free. Guarantee. Urgent. Act now. Some lists even include "hello".
If those words reliably sent email to spam, half of all legitimate business email would never arrive. Your bank uses "free". Your airline uses "urgent". They land in the inbox fine.
How filters actually work now
Modern filters at Gmail and Microsoft rely mostly on reputation and engagement. Who sent this, how do recipients usually react to this sender, and does this message look like other messages people marked as spam?
Content plays a part, but it's pattern-based, not a list of banned words. A filter is far more interested in:
- Whether the email looks like a template sent to thousands of people
- What domains the links point to
- How the HTML is built
- Whether the message matches what this sender usually sends
Content problems that do matter
Links
- Link shorteners (bit.ly and similar) are heavily abused by spammers. Never use them in cold email.
- Links to a domain with a poor reputation, including some free website builders and file-sharing sites.
- Too many links. A first cold email needs zero or one.
- Mismatched links, where the visible text shows one URL and the actual link goes somewhere else.
Images and attachments
- An email that's mostly an image with little text is a classic spam pattern.
- Attachments on a first email from an unknown sender are risky. PDFs and especially ZIP files.
HTML
- Heavy templates with tables, background images and lots of styling look like newsletters, not one-to-one emails.
- Hidden text, tiny fonts or white-on-white text are red flags.
- Messy HTML pasted from a word processor can trigger filters on its own.
Sameness
If 500 emails go out with identical text, filters notice. Real personalisation helps, not just {first_name}, but a line that's actually specific to each company or role.
Be careful with "spintax" that randomly swaps words. Done badly, it produces odd sentences that read as spam to humans, which means more spam reports.
Where words do make a difference
Words matter to people. A subject line like "FREE GUARANTEED LEADS!!!" won't get filtered for the word "free". It'll get reported as spam by the reader. Those reports are what actually damage your reputation.
So write the way you'd write to one person:
- Plain subject lines, lowercase is fine
- No exclamation marks in the subject
- Short, clear sentences
- One question at the end
Our post on cold email copy goes deeper.
Fix things in the right order
If you're landing in spam, check authentication, reputation and list quality first. Then look at links, images and HTML. Rewording "free" to "complimentary" comes last, and usually changes nothing.
Want us to look at your email? Send it over and we'll run a placement test on it.