To get the results as close to your real email campaign as possible, it is advised to send the message to the seed list the same way you are are sending it to your recipients.
If you send your email campaigns by putting many email addresses in the email’s To: or CC: field, you can do the same when running a test in GlockApps. Keep in mind that the full seed list contains 100+ email addresses. The best practice is to use no more than 25 email addresses in the To: or CC: field at a time. You can use a split seed list provided by GlockApps and send the same message with the same test id code to each segment. The results will be added to the same report. The test will consume one credit our of the balance.
Read more: Seed Based Email Tests: Best Practices