Inbox Placement Rate
The percentage of delivered emails that land in the primary inbox versus spam.
1 min readLast updated Apr 2026
Quick Reference
CategoryEmail Marketing & Klaviyo
Related Terms2
The percentage of delivered emails that land in the primary inbox versus spam.
Why It Matters
An email in spam is almost as bad as undelivered—open rates for spam folder emails are near zero. Gmail's Promotions tab and spam filters mean 'delivered' doesn't guarantee visibility. Inbox placement is the true measure of whether your emails are seen.
Practical Example
Scenario
A supplement brand uses a seed list test showing 85% inbox placement—15% going to spam or Promotions.
Calculation
If they send to 50,000 subscribers, only 42,500 land in primary inboxResult
After improving authentication and reducing promotional language, inbox placement rises to 92%, reaching 46,000 primary inboxes—an 8% increase in effective reach.
Pro Tips
- 1Use inbox placement testing tools (Glockapps, Inbox Monster) before major campaigns
- 2Gmail's Promotions tab isn't spam—emails there still get ~50% of primary inbox engagement
- 3Encourage replies and engagement, which signals to ISPs that recipients want your emails
- 4Avoid spam trigger words in subject lines: 'FREE', 'Act Now', excessive caps and punctuation
Common Mistakes to Avoid
Assuming high deliverability means high inbox placement—they're different metrics
Ignoring Gmail Promotions tab, which holds legitimate marketing emails
Using the same content for all ISPs when different providers have different filter sensitivities