Module 2 · Chapter 7

Spam triggers and how to avoid them

10 min read

Even with perfect authentication, warmed inboxes, and strong domain reputation, the content of your email can still trigger spam filters. Modern filters analyze everything from individual words to formatting patterns to sending behavior. This chapter is your definitive guide to avoiding content-based spam triggers.

Spam trigger words and phrases

Certain words and phrases are statistically associated with spam. Using them does not guarantee your email lands in spam — context matters — but they increase the risk, especially when combined with other negative signals.

High-risk words to avoid

Category Examples
Urgency / Pressure "Act now," "Limited time," "Urgent," "Don't miss out," "Expires"
Money / Offers "Free," "Discount," "Best price," "No cost," "Guaranteed," "Special offer"
Exaggerated claims "100% guaranteed," "Double your revenue," "Incredible results," "You won't believe"
Financial terms "Earn money," "Cash bonus," "Credit card," "Investment opportunity"
Manipulative language "Click below," "Buy now," "Order today," "As seen on," "Dear friend"

The key rule: write like you would email a colleague. You would never write "ACT NOW to receive a GUARANTEED 300% increase" to a coworker. If a sentence sounds like an advertisement, rewrite it.

Key insight

A single spam trigger word will not sink your email. Spam filters look at the overall score — the combination of words, formatting, links, sender reputation, and engagement history. But every trigger word adds to that score. Keep your copy clean, and you stay well below the threshold.

Formatting triggers

How your email looks is as important as what it says. Spam filters analyze the structure and formatting of your email to determine whether it is a personal message or a marketing blast.

Triggers to avoid

  • ALL CAPS in subject line or body. "QUICK QUESTION ABOUT YOUR SALES PIPELINE" screams spam. Use lowercase or sentence case only.
  • Excessive exclamation marks. One is fine in rare cases. Multiple (!!!) are a trigger. Zero is ideal for cold email.
  • Colored or styled text. Red text, different font sizes, or bold formatting throughout the email all raise flags. Stick to default styling.
  • HTML-heavy emails. Complex HTML with tables, divs, and inline styles has a high HTML-to-text ratio. Spam filters use this ratio as a signal. Pure plain text is safest.
  • Large or elaborate signatures. Signatures with images, banners, social icons, and legal disclaimers dramatically increase your HTML ratio. Keep signatures minimal: name, title, company, and optionally a URL.

Links and tracking

Links are one of the most scrutinized elements in email filtering. Spam filters evaluate the number of links, the domains they point to, and whether they use tracking redirects.

  • Zero links is ideal for first touches. Your first email should aim for zero links. The goal is a reply, not a click.
  • One link maximum. If you must include a link (e.g., a Calendly link in a follow-up), keep it to one. Two or more links significantly increase spam risk.
  • Avoid link shorteners. Bit.ly, TinyURL, and similar services are heavily associated with spam and phishing. Use full URLs.
  • Custom tracking domains. If your platform rewrites links for click tracking, ensure it uses your custom tracking domain (track.yourdomain.com) rather than a shared domain.

Watch out

Open tracking pixels are invisible images embedded in your email. They are technically a link to an image on a tracking server. Some spam filters detect and penalize them. Consider disabling open tracking for your initial emails, especially while your domain is still building reputation. Reply rate is a more reliable metric anyway.

Images and attachments

Images

Do not include images in cold emails. No logos, no screenshots, no product images. Any image shifts your email from looking like a personal message to looking like a marketing email. Spam filters notice this immediately.

The one exception: personalized screenshots or videos (like a short Loom recording) can work in later follow-ups once your domain has established reputation. But never in the first email, and never with a brand-new domain.

Attachments

Never send attachments in cold emails. They are a major spam trigger and a security red flag. No PDFs, no slide decks, no documents. If you need to share a resource, offer to send it if they reply with interest. This also gives you another touchpoint and conversation starter.

Sending pattern triggers

Beyond content, spam filters analyze how you send:

  • Volume spikes. Going from 10 emails yesterday to 100 today is a red flag. Keep volume consistent day to day. Gradual increases only.
  • Identical content to many recipients. Sending the exact same email body to 200 different people looks like a spam blast. Even minor variations (personalized opening lines) differentiate your emails enough.
  • Sending bursts. 30 emails in 5 minutes looks automated. 30 emails spread over 8 hours looks human. Use randomized delays.
  • Sending outside business hours. Emails sent at 3 AM consistently are unusual for legitimate business communication. Keep sending within 8 AM–6 PM in the recipient's timezone.
  • High bounce rate. If more than 3% of your emails bounce, email providers interpret this as you sending to unverified or purchased lists — a spam signal. Verify all addresses before sending.

The unsubscribe question

Should you include an unsubscribe link in cold emails? This is a debated topic in the cold email community.

Arguments for: CAN-SPAM requires it for commercial email. Google and Yahoo announced stricter requirements in 2024 for bulk senders. Including one shows respect for the recipient.

Arguments against: Adding a link increases spam risk (especially from new domains). Cold email is one-to-one outreach, not bulk email. An unsubscribe link makes it look like a marketing email rather than a personal message.

The pragmatic approach: If you send fewer than 5,000 emails per day (which most cold emailers do), the 2024 Gmail/Yahoo bulk sender rules technically do not apply to you. However, you should always honor opt-out requests promptly when someone replies asking to be removed. Many outreach platforms handle this with a plain-text opt-out line like "If this isn't relevant, just let me know and I won't reach out again" — which doubles as a soft CTA.

The pre-send deliverability checklist

Run every campaign through this checklist before activating:

  • No spam trigger words in subject line or body
  • No ALL CAPS, no excessive punctuation
  • Plain text format (no images, no heavy HTML)
  • Zero or one links (no link shorteners)
  • No attachments
  • Minimal signature (name, title, company)
  • Email list verified (bounce rate projection under 2%)
  • Personalization tokens checked (no blank or broken merge fields)
  • Sending volume within per-inbox daily limits
  • Randomized delays configured between emails
  • Sending window set to business hours in recipient's timezone
  • Test email scored 9+ on mail-tester.com

Following this checklist will not make you immune to spam filters, but it eliminates the self-inflicted wounds that account for most deliverability problems. The next and final chapter of this module covers ongoing monitoring — how to track your deliverability health and fix problems when they arise.