Inbox placement testing

Inbox placement testing (also called seed list testing) lets you check exactly where your email lands — inbox, promotions tab, or spam — at Gmail, Outlook, Yahoo, and 20+ other email providers before or after a send. Results return in under 5 minutes.

How seed list testing works

InboxEagle maintains a panel of real mailboxes at 20+ email service providers. To run a placement test, you send your campaign to InboxEagle’s seed addresses using the same sending infrastructure you use for real subscribers. InboxEagle checks each seed mailbox and reports back the placement per provider.

Supported providers include: Gmail, Outlook, Yahoo, AOL, Apple Mail, and 15+ additional providers covering the major mailbox destinations for most email programs.

Seed list testing vs ongoing placement monitoring

Approach	When it runs	Data source	Best for
Seed list test	On demand, triggered by you	InboxEagle panel mailboxes	Pre-send validation; one-time checks
Ongoing monitoring	Continuously, from your real sends	Real subscriber engagement data	Long-term trends; volume-based signals

Both are complementary. Use seed testing to validate placement before a high-stakes send; use ongoing monitoring to track placement trends over time across your real subscriber base.

Run a placement test

1. Open Inbox Placement Tests

   In the InboxEagle app, navigate to Deliverability → Inbox Placement Tests.

2. Copy the seed list addresses

   InboxEagle provides a list of seed email addresses. Copy all of them.

3. Send your campaign to the seed addresses

   Add the seed addresses to your send list in your ESP and send your campaign exactly as you would to real subscribers — using the same sending domain, IP, configuration set, and from address.

4. Wait for results

   Return to InboxEagle. Results populate within 5 minutes as InboxEagle checks each seed mailbox.

5. Review placement by provider

   The results view shows inbox, promotions, and spam placement rates per provider, plus the subject line and preview text as received at each mailbox.

Caution

Send to seed addresses using the same infrastructure as your production sends — same sending domain, IP address, configuration set (AWS SES), and from address. Sending from a different IP or subdomain gives misleading results. Do not warm up IPs using seed addresses.

Reading your test results

Each placement test result shows:

Column	What it means
Provider	The mailbox provider (Gmail, Outlook, Yahoo, etc.)
Inbox %	Percentage of seed mailboxes where the message landed in the primary inbox
Promotions %	Percentage that landed in a promotions or bulk tab (Gmail Promotions, etc.)
Spam %	Percentage that landed in the spam or junk folder
Missing %	Percentage of seed mailboxes where the message did not arrive
Authentication	SPF, DKIM, and DMARC pass/fail as received at each provider

Tip

A high Missing % at a specific provider often indicates a block or rate limit at that provider, not just filtering. If more than 20% of seeds at one provider are missing after 10 minutes, investigate blocklist status for your sending IP.

When to run a placement test

Run a seed test in these situations:

• Before a high-volume or high-stakes campaign (seasonal send, product launch, re-engagement)
• After changing your sending domain, IP, or ESP configuration
• After updating your DKIM keys or DMARC policy
• When investigating a sudden drop in click or open rates that may indicate spam folder placement
• When launching a new sending subdomain or dedicated IP

Next steps

• Campaign history — View post-send delivery and authentication status per message
• Improve inbox placement — Actionable steps to lift your placement rates
• Blocklist detection — Confirm your sending IPs are not listed before testing

Run a placement test →