How to Run an Inbox Placement Test (and Read the Results Properly)
"I sent a test to my Gmail and it landed in the inbox, so we're fine."
We hear this a lot. Unfortunately, your own Gmail is the worst possible test. It has history with you. You've emailed yourself, replied, maybe marked things as "not spam". Gmail treats your mail differently from how it treats a stranger's inbox.
What a placement test does
A placement test sends your email to a seed list: a set of mailboxes across Gmail, Outlook, Yahoo, and business mail systems that have no relationship with you. The tool then checks where each copy landed:
- Inbox
- Spam or Junk
- Promotions or other tabs
- Missing (not delivered at all)
Tools like GlockApps and similar services offer this. Many warm-up tools also include basic placement checks.
How to run one properly
- Send from the real mailbox you use for the campaign, not a test account.
- Use the real email, with the same subject, body, links and signature.
- Send through the same tool you use for campaigns, so tracking and headers match.
- Test each domain separately. One clean domain doesn't mean all ten are clean.
- Repeat weekly. Placement changes. A domain that was fine in August can slip in September.
Reading the results
| Result | What it usually means |
|---|---|
| Mostly inbox everywhere | You're in good shape |
| Spam at Gmail only | Gmail reputation or content issue. Check Postmaster Tools |
| Spam at Outlook only | Microsoft is stricter on new domains and volume. Slow down |
| Spam everywhere | Authentication, blocklist or a bad link. Start with the basics |
| Missing | Rejected. Check bounce logs and blocklists |
| Promotions tab | Not ideal for cold email. Simplify HTML, remove images and tracking |
Isolating the cause
If results are bad, change one thing at a time and test again:
- Same email, plain text, no links, no tracking. If it now lands in inbox, the problem is content or links.
- Same email from a different, well-warmed domain. If that lands in inbox, the problem is the original domain's reputation.
- Check headers for SPF, DKIM and DMARC. Fails here explain everything.
A note on seed test limits
Seed mailboxes don't behave exactly like real prospects. They don't reply or open in the same way. So treat placement tests as a warning system, not a perfect measure. If seed tests say 90% inbox but your reply rate collapsed, trust the reply rate and investigate.
How we use it
For clients, we run placement tests on every domain before the first campaign and weekly after that. Together with blocklist monitoring and reputation dashboards, it means problems get spotted in days, not after a month of silent spam placement. Ask us about deliverability monitoring.