[Cyberdog]

What a very websitey web site. My first thought when I saw that home page was "boy, I bet if I keep scrolling, there's going to be empty areas on the page where things obnoxiously animate into place" and BOY HOWDY.

For your free tier which claims to offer unlimited emails, how are you stopping people from signing up and using it to blast out spam until you find it and kill their account (after which they will just sign up for another free account)? Services like these need to be very careful they're not sending out spam lest spam daemons start dropping all messages from their servers, causing emails from legitimate users to never hit their destination. If you don't have some extreme limits on this (like maybe one outgoing message per five minutes) I would suggest you do away with the free tier. Given the enormity of the problem of email spam and the disastrous effects being seen as a spam collaborator will have on your legit users, there's really no shame in getting a card on file and maybe even doing other identity validation before letting users send email with a tool like this.

[memcg]

Amen. I get a lot of spam from senders that abuse free services (url shorteners, image hosting and redirect links). It could be a huge waste of time for you.