Deliverability

How to test email deliverability (placement tests + seed lists)

Don't guess — test. Use a seed list of inboxes across providers to see where your mail lands (inbox vs spam vs promotions), check your auth, and monitor reputation. Here's the testing routine.

19 Apr 2026 6 min readBy Autocloz Editorial, Deliverability team
How to test email deliverability (placement tests + seed lists)

Short answer: test email deliverability with a seed list — a spread of inboxes across Gmail, Outlook, Yahoo and others that you send to, then check where each copy lands (inbox / spam / promotions). Pair it with an auth check (SPF/DKIM/DMARC all passing) and reputation monitoring (Google Postmaster Tools). A seed test tells you the truth open rates can't.

The testing routine

  1. Placement test — send to a seed list; record inbox vs spam vs promo per provider.
  2. Auth check — confirm SPF, DKIM, DMARC all pass on the sending domain.
  3. Content check — run the copy through a spam checker.
  4. Reputation — watch Postmaster Tools for complaints + domain reputation.
  5. Re-test after changes — warmup, new domain, new template.

Why test before scaling

Blasting 10,000 emails to discover you're in spam is an expensive way to learn. A 50-inbox seed test tells you first.

Autocloz builds in placement monitoring + auth checks so you test continuously, not just once before launch.

> Start free — test placement before you scale the send.

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Every tactic in this article is implemented behind the Autocloz dashboard.