Definition
Inbox placement testing uses a network of seed email addresses across Gmail, Outlook, Yahoo, and other ISPs to measure exactly where your campaign lands. Unlike aggregate metrics that estimate placement, seed testing gives definitive per-ISP results.
How It Works
- You send your campaign to a seed list maintained by a testing service
- The service checks each seed inbox and reports whether the email arrived, went to spam, or was blocked
- Results are broken down by ISP, allowing you to identify which providers have issues
When to Test
- Before launching to a new ISP or list segment
- After significant content or infrastructure changes
- When aggregate metrics suggest deliverability has declined
- On a regular schedule (monthly or quarterly) for ongoing monitoring
Tools
Litmus, Email on Acid, GlockApps, and 250ok provide automated inbox placement testing with seed lists across 50+ ISPs and email clients.
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.
Abandoned Cart Email
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AIDA Model for Email
The AIDA model (Attention, Interest, Desire, Action) is a classic copywriting framework used to structure email campaigns that guide subscribers from awareness to conversion.
AMP for Email
AMP for Email is a Google-developed framework that allows email messages to include interactive elements like forms, carousels, accordions, and live content. It turns static emails into dynamic, interactive experiences directly inside the inbox.
Anchoring Effect in Email Marketing
The anchoring effect is a cognitive bias where the first piece of information presented (the anchor) influences subsequent decisions, used in email to frame pricing and value perception.
Announcement Email
An announcement email is a dedicated campaign that communicates a specific update, milestone, or change to subscribers, from product launches and feature releases to company news and events.