I’ve been working on a small side project that involves processing incoming email. In particular, it’s an app that needs to do something for each email it receives from (hopefully paying!) users.<p>I am not interested in storing user mail, so SES is just too costly, at least according to a quick worst-case calculation.<p>That leaves me with two options:<p>1. Self-hosted Postfix<p>2. Mail service like Mailgun<p>With (1), there is no need to worry about overages, but scaling the mail server might be challenging.<p>The advantage of (2) over SES is that you are only charged a flat fee for each email, regardless of size. Emails are then automatically deleted after some period of time. Scaling up and down is easy.<p>For now, I am using Mailgun, but I am writing the mail processing daemon in a way that will make it easy to transition to Postfix, if needed.<p>Also, I decided to write the mail processing backend in Rust, so I’ve been learning the language as I go!