Definition
A heatmap aggregates click data from an email campaign and displays it as a colour-coded overlay. Hotter colours (red, orange) represent areas with the most clicks. Cooler colours (blue, grey) represent ignored areas.
What Heatmaps Reveal
- CTA visibility: Whether your primary call-to-action is actually being seen and clicked
- Link competition: If secondary links are distracting from the main CTA
- Below-fold engagement: Whether readers are scrolling and clicking further down
- Mobile vs desktop patterns: How click behaviour differs by device
- Image clicks: Whether subscribers are trying to click images (indicating they expected them to be linked)
Tools
Most ESPs offer built-in click maps. Dedicated tools like Litmus and Email on Acid provide more detailed heatmapping with scroll-depth overlays and device-specific views.
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
Accessible CTA (Email)
An accessible CTA is a button or link coded with sufficient colour contrast, visible focus states, descriptive screen-reader text, and a minimum touch target of 44×44 pixels.
ARPU (Average Revenue Per User)
ARPU (Average Revenue Per User) is a metric that measures the average revenue generated per email subscriber over a specific period, used to evaluate list value and campaign effectiveness.
Attention Rate
Attention rate is the percentage of email opens that last longer than 5 seconds, distinguishing genuine reads from passive opens, preview-pane views, or Apple MPP auto-loads.
Bounce Rate
Email bounce rate is the percentage of emails that were rejected by the receiving server before reaching the recipient. It is a key indicator of list health and data quality.
Campaign Internal Rate of Return (IRR)
Campaign IRR is the annualised return rate earned by an email campaign, accounting for the timing and magnitude of costs and revenue across the campaign's full lifecycle.