When you implement the Return Path Seed List for your campaigns you send to Return Path Platform or Inbox Monitor, it is ideal to evenly distribute the seed addresses throughout your list. Placement of the Return Path Seed List at the beginning or end of a campaign does not present the most accurate delivery results because the seed addresses are separated from the bulk of your campaign and may not experience the same treatment as the rest of your mail stream.
However, if you have to add the seed list to the beginning or end of your email campaign, Return Path recommends adding it to the end.