Email Marketing Term
What is Spam Filter?
Software that automatically detects and blocks unwanted or malicious emails from reaching inboxes.
Spam filters use multiple signals to evaluate emails:
**Content analysis**: Trigger words (FREE, WINNER, ACT NOW), excessive punctuation, suspicious links, image-heavy emails.
**Sender reputation**: Domain age, authentication, complaint history, blacklist status.
**Engagement signals**: How recipients interact with your emails over time.
**Technical factors**: Valid authentication (SPF/DKIM/DMARC), consistent sending patterns, proper formatting.
Modern spam filters use machine learning, making them harder to game. The best strategy is sending emails people actually want.
Examples
- Gmail spam filter catches 99.9% of spam
- Trigger words like "FREE CASH" increase spam score
- High complaint rates trigger automatic filtering
Tips for Spam Filter
- ✓Avoid spam trigger words in subject lines
- ✓Maintain good sender reputation
- ✓Include clear unsubscribe links
- ✓Balance text and images (60/40 ratio)
Related Terms
Test Your Subject Lines
Put your email marketing knowledge into practice. Analyze your subject lines for free.
Try the Subject Line Tester