How to Use Seed Testing to Monitor Deliverability

Seed testing is the most practical and reliable method for monitoring cold email deliverability. Here is how to implement it.

What seed testing is

Seed testing involves sending test emails from your cold email accounts to a set of email addresses (seeds) that you control across multiple providers. You then check whether each test email landed in the inbox, spam, or was not delivered.

Setting up seed accounts

Create test email accounts at each major provider: Gmail (personal), Google Workspace, Outlook.com, Microsoft 365, Yahoo, and any other provider relevant to your audience. Use unique, realistic-looking addresses.

Running a seed test

Send a test email from each of your cold email accounts to all seed addresses. Use content that resembles your actual campaign copy — not "this is a test" but a realistic cold email. After sending, check each seed account and record the result: inbox, spam/junk, promotions tab, or not received.

Automated seed testing

Manual seed testing is time-consuming. Tools like the deliverability checker automate this process, sending test emails and reporting placement across providers.

Interpreting seed test results

90%+ inbox: Healthy. Proceed with campaigns. 70-89% inbox: Concerning. Some providers are filtering. Investigate which providers are problematic and address the specific issues. Below 70% inbox: Critical. Pause campaigns and diagnose. Check authentication, warmup health, and blacklist status.

Testing cadence

Before launching any new campaign or new account. Weekly during active campaigns. After any infrastructure changes (DNS, warmup adjustments). Immediately if you notice a drop in reply rates.

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