What is inbox placement?
Also called: inbox placement rate, seed testing
Inbox placement is the share of delivered mail that lands in the inbox rather than spam or a promotions tab. It cannot be measured from your own sending logs, because a provider that files a message as spam still reports it as delivered. It is estimated with seed lists or provider feedback.
Delivery rate counts messages the receiving server accepted. Placement asks where they went afterwards, and the receiving server does not tell you.
Seed testing is the usual approach: send to a set of monitored addresses across the major providers and see where each copy lands. It is a sample, not a census, so treat it as directional. Google Postmaster Tools and Microsoft SNDS give provider-side data for their own users.
Placement differs by provider and by recipient. Gmail, Outlook.com and Yahoo each run their own filters, and engagement history means the same message can land in one person's inbox and another person's spam folder.
A fall in placement with no change in delivery rate almost always points at reputation or authentication rather than copy. Rule out bounces and a blocklist listing before rewriting the email.
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By SimpleVerifier Team · Last reviewed 2026-10-13 · All 50 glossary terms