Wrong approach. You want to give me a dead simple API so that I can send highly personalized postcards in one's, two's or ten's to specific customers I'm marketing to. Should be less complicated than the Stripe API and it should have hosted call to action that lets the recipient confirm they got the card so you can track and report value. What you have here has been done before many times.
What you're describing is lob.com (which we use and love). It may be the wrong approach, but we've sent 50k+ postcards in 2 months with a 50% margin... delivering a 5x LTV return on investment. So, it seems to be working for us. I guess maybe this is the wrong audience as it's more of a service for marketers than developers. Scout is part software part marketing service.
Hey HN, we've built a way to market with postcards. We're built on top of Lob.com and we help you find list, design the best postcard, customize cards, and get a return on your postard direct mail campaign.
-Jordan
founder
my email is my first name at the domain I posted if you wanna reach out.