Self-hosting the mail-composing, mail-merging and tracking functions while using third-party SMTP is well-trod territory. The former can be done on a pretty basic box and the latter, at scale, is a heavy lift.
My guess is Plunk is for people who need a Mailchimp-like offering at a lower-than-Mailchimp price point.
My guess is Plunk is for people who need a Mailchimp-like offering at a lower-than-Mailchimp price point.