Spam trigger words that are killing your deliverability.
Content-based spam filters scan your email for patterns associated with spam. Some words and phrases flag immediately. This reference covers what to avoid and why.
How content filtering actually works
Spam filters don't just look for individual words -- they analyze patterns. A single "free" in your email won't kill you. But "free" plus "limited time" plus "act now" plus an image-heavy HTML email from a new domain with no engagement history? That's a spam cocktail. Content filtering is one signal among many: domain reputation, authentication, engagement history, and sending patterns all matter. But content is the one you control on every email. This reference helps you write clean copy that doesn't trigger unnecessary flags.
What's in this reference
- High-risk trigger words and phrases (financial, urgency, promotional)
- Medium-risk patterns that compound with other signals
- Safe alternatives for commonly flagged language
- HTML vs. plain text: how formatting affects filtering
- Link patterns: tracking pixels, URL shorteners, redirect chains
- Subject line triggers vs. body triggers
- Provider-specific quirks (Gmail vs. Outlook vs. Yahoo)
- Testing methods: how to check your email before sending
Where to go from here
Avoiding spam words is necessary but not sufficient for good deliverability. Your domain reputation, authentication setup, and sending patterns matter more. Check our Deliverability Guide for the full picture, our Domain Warmup Guide for building sender reputation, and our Cold Email Templates for copy that's proven to avoid spam filters while getting replies.
Frequently asked questions
Will using one spam word get me flagged?
Almost never. Spam filtering is pattern-based, not word-based. A single flagged word in an otherwise clean email from a reputable domain won't hurt. It's the accumulation of signals that triggers filtering.
Is this list complete?
No list is complete -- spam filters evolve constantly. This reference covers the most common and impactful triggers as of the last update. We add new patterns as inbox providers update their algorithms.
My email doesn't have any spam words but still goes to spam. Why?
Content is one of many signals. If your domain reputation is low, authentication is misconfigured, or your sending patterns look automated, you'll hit spam regardless of content. Start with our Deliverability Guide.
Write emails that land in the inbox.
Book a call and we'll audit your current email copy for deliverability issues.