Inbox placement
Where an accepted message ends up for the recipient: the inbox (or one of its tabs) or the spam folder, a choice the mailbox provider makes and does not report back.
What it means
Inbox placement is the part of deliverability that SMTP logs cannot show. After a server accepts a message, the provider's filters choose the folder and the sender is not told. Gmail's Postmaster Tools adds a warning: mail that Gmail sends to spam automatically is not reported as spam by users, so a sender filtered to spam can show a low spam rate.
Placement is decided per message from the sender's IP and domain reputation, authentication, content and the recipient's own actions: in Gmail, reporting mail as spam or marking it as not spam changes how similar mail from that sender is filed.
Senders estimate placement with seed tests, provider dashboards and engagement trends. M3AAWG notes that a drop in opens or clicks can indicate that mail is going to the junk folder.
Related terms
On this site
Sources
What this definition rests on. The wording is ours; the facts are theirs.
- Gmail Help: Postmaster Tools dashboardssupport.google.com
- Gmail Help: Report spam in Gmailsupport.google.com
- Google: Email sender guidelinessupport.google.com
- M3AAWG Sender Best Common Practices, version 4.0 (August 2026)m3aawg.org
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