@jwildeboer I'm similarly thankful to the contributors of Haraka. It was very easy to deploy SMTP/MX at scale with custom logic (Redis, delivery to apps) from containers.

Is Postfix any better at having multiple instances sharing a single queue volume?

GitHub - haraka/Haraka: A fast, highly extensible, and event driven SMTP server

A fast, highly extensible, and event driven SMTP server - haraka/Haraka

GitHub (github.com)