Hmm...I'm surprised I hadn't considered this before. We could drastically increase our audience count for each send by making thank you emails operational, which they should be, in my opinion, since they've been requested.
What's strange, though, is I don't feel like (as a lead) I've been missing out on any emails or thank you's. I would think, with how many emails I get from doing preflight campaigns to myself, that I would've noticed getting blocked. I'm not sure if you have an answer for that, but thanks for your help.