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Docs/Deliverability/Seed list placement tests

Seed list placement tests

Updated Apr 1, 2026 · 4 min read

What a seed test measures, what InboxLee runs today, and how to run one yourself.

On this page · 3
  1. What InboxLee runs today
  2. What a scored test surfaces
  3. Running your own test in the meantime

Seed list testing is the only direct way to measure inbox placement. A delivery report tells you a message was accepted. Only a seed test tells you which folder it landed in.

What InboxLee runs today

InboxLee does not currently operate fleet-wide seed tests. InboxLee never sends - no probe traffic originates from us - so a placement test exists only when you start one: you add the InboxLee seed addresses to one of your own campaigns, and we read which folder each seed copy landed in.

The seed-reader infrastructure is still being built, so until it ships the placement panel shows no measured number rather than an estimated one. We would rather show you nothing than a guess.

What a scored test surfaces

  • Primary inbox placement rate - the headline metric.
  • Per-provider breakdown - Gmail vs M365 placement often diverges.
  • Trend line - week-over-week change is more meaningful than day-to-day variance.
  • Per-mailbox detail - one bad mailbox can drag a cohort.

    • Running your own test in the meantime

  • Build a seed list of inboxes you control across Gmail, Workspace, Outlook, M365, and Yahoo.
  • Add the seeds to a live campaign so the message travels exactly the path your real sends take.
  • Record where each copy lands - primary, promotions, spam, or missing entirely.
  • Repeat weekly at the same time of day and read the trend, not any single run.
    • Sustained primary placement under 70% is the point to stop sending and investigate. Above 90% is healthy.
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