Bonus: They straight up declined my business because it was too marketing-y for them.
What was too marketing for them? A 100% opt-in list that reminded customers when a product was in stock. Fully made in-house, with captcha, privacy policies, opt-out, and with the user typing their email and name, the complete works for a one-time reminder email.
Nope far too marketing related for them.
TLDR: Minimum tier was $400 signup + $1,375/year for up to 100,000 mails/year.
[1] https://returnpath.com/wp-content/uploads/2015/06/Return-Pat...