A bit unrelated:

What is the cheapest provider for transactional E-Mail through an API?

Mailchimp is quite expense. A few solutions are a bit cheaper but not that much.

I used to have my own mailserver using Roundcube and my E-Mails never ended in the spams. So it quickly gets more economic to run my own mail server. Only problem is that it is quite a headache to manage. Can't some one create a 10x cheaper alternative to Mailchimp since sending E-Mails comes at almost no cost?