It checks where mail actually arrives by reading destination inboxes directly — seed mailboxes monitored over IMAP across Gmail, Outlook, and more — rather than inferring delivery from send logs or tracking pixels. It separates Inbox from Spam and Promotions, giving an honest placement signal that sender-side metrics and manufactured-engagement warmup pools cannot provide.
Most "deliverability" numbers are inferred from the sender's side: accepted-by-server counts, or open rates from tracking pixels. Neither tells you the one thing that matters — which folder the recipient sees. Receiver-side placement measurement answers that directly. You maintain a set of seed mailboxes you control across the major providers, send your campaign (or a representative copy) to them, then read those inboxes over IMAP and classify each result: Inbox, Spam, or Promotions, broken out by provider. The output is an observed placement rate, not a guess. Two honesty constraints make this trustworthy rather than theatrical: the panel must be owned and disclosed in scope — it is a sample, not a census of the whole internet — and it must not be confused with manufactured-engagement warmup, which manipulates reputation instead of measuring it. Done right, placement measurement is the feedback loop that makes everything else — authentication fixes, warmup pace, content changes — verifiable. Humerly provides this as part of the control plane: measured inbox placement using owned seed mailboxes (sample-scoped), alongside pre-send audit and continuous monitoring.