A seed list is a list of email addresses that is automatically added to intended recipients for each email campaign. Addresses from the list are monitored by a software to control if messages are received. Sometimes it can also be used to monitor how messages render. Thus, a seed list system allows marketers to know their inbox placement rate and sometimes to visualize email rendering.
The seed list may be created in-house or be proposed by a dedicated third-party vendor. It is often an additional or included service of major ESP platforms.
A seed list contains addresses from main ISPs and webmail services and must be representative for each country.
Seed lists are less effective for B2B practices as it is difficult to have company addresses in a seed list.
An example of seed list integrated in an ESP platform: