Ask HN: How do you send schedule/recurring emails?

I'm working on a site that needs to send regular reminder emails to our clients. I was shocked to find that no one seems to be selling this as a service. You can get "email as a service" (Mailgun, Mail Grid, Mandrill, etc) and you can get "cron as a service", but not the two married with each other. Also, there are a few wrinkles that make it harder than just using both services together.

So I'm testing out the idea of offering this as a server: timelyemail.com. It's essentially Mailgun and cron together, but in a much more developer friendly way so you can push or pull both content and recipients, and easily modify your scheduled emails.

Any and all feedback is greatly appreciated... thanks in advance!