When Mozilla launched a VPN I was really excited to have a way to 'subscribe' and support the org, in that vein I'd just like to say that I'd pay up to $20 a month for a web-based email client with features like that that one really popular one that's free (unless you place value on your privacy).
I don't know if anyone else feels the same way but thought I should put it out there (apologies if this is common suggestion, I'm new to these forums).