[dna_polymerase]

> Are you saying Substack users pay per email sent to their paying subscribers?

No, I was referring to the whole Marriott thing. If you book a Marriott hotel with an aggregator (like Kayak), Marriott has to pay for that booking. If you do it the next week again, Marriott has to pay again.

Substack fees work the same, you pay a fee to Substack whenever a person renews (transaction).

So to make the loop back, no the Kayak example works the same way as Substack does. It just happens to be the case, that customer retention is higher with Substack (or lower-cost transactions in general)