I appreciate the response. Anecdotal situation - I have to admit the 1 domain thing is a drawback for me. In order for me to commit the financials to this I'd need to be able to use it for more domains (ie, spread the costs across my personal businesses as well). As a solution for 1 domain only it has the feel of Silicon Valley millionaires solving problems for Silicon Valley millionaires.

There is no break-even point on this because by default the subscription is more than Fastmail, including their business offering, and even amortizing the device over a decade is still a stretch (what device lasts a decade anymore?). I think what I'm realizing is that even with a gross annual household income over half a mil USD is that I can put a price on email and it's lower than this.

All of that said I do think you've got a neat product. The EC2 solution for tunneling is novel and explains the higher subscription cost. I hope you are successful because I'm curious to see what version 2 would be like service/pricing wise.