Email Seed testing

Even though measuring your campaign performance and checking IP/domain reputation in the free sources (Google Postmaster, Microsoft SNDS, block lists) can give you some insight on how your emails perform in terms of getting to the Inbox vs. Spam delivery, the only way to measure your actual Inbox placement is to use seed testing. Seed testing services are offered by 3rd party companies outside Leanplum.

What are seed lists and how can you utilize them?

Seed accounts are dummy email accounts in various Inbox Service Providers (ISPs). They are owned by the respective testing service and are created and used solely for measuring inbox placement. Popular service providers are Validity, Email on Acid, Litmus and so on. What are the benefits and how to get the most of seed testing:

  • Customize the seed list, so it reflects your user base accurately - if you don’t have a large user base in Russian or Chinese ISPs, you don’t need to include seeds in these providers; if your user base is located in Europe, you may have to include popular local providers instead. 
  • Pre-test each campaign by targeting the seed list first - this way you will know how the campaign will perform in advance 
  • A seed test will show you how fast your emails are accepted in the various ISPs
  • You can figure out which ISPs will block your email and what content/subject lines work best

How to use a seed list in Leanplum?

In order to send an email to a seed list, the list needs to be uploaded to Leanplum. You can import users in Leanplum using one of the following methods:

To prepare the file, you should:

  1. Load seed addresses under “”
  2. Add unique names (User IDs) for each seed under “userId”
  3. You may add an additional custom attribute that will help you distinguish them from your regular users

Once the upload is complete, you should target the list separately, before deploying the actual campaign. This is in order to avoid skewing your actual metrics as these accounts do not engage.


If you have issues with the file upload or need advise on improving your inbox placement, you can reach out to

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