Thanks, someone who has sent billions of emails is exactly who I need to ask.

Regarding 'set and forget': I agree once infra is stable, it stays. But I see the value when the application layer changes—tweaking templates, switching providers, or DNS updates. Do you still feel mocks are enough there?

Regarding PII: You're 100% right on hygiene. The encryption (ML-KEM-768) is just a 'safety net' for the human errors.

Regarding FSL-1.1-MIT: Very interesting suggestion. I will investigate it.

Honest question: At your scale, is this a niche tool or is 'mock and pray' just the industry standard for a reason? Don’t worry about hurting my feelings, I just need to know if I'm solving a real problem.

For a bit more context, most email infrastructures I’ve worked with are for transactional and marketing DTC and B2B companies. I would read my response in this context.

Re one-time setups and one-time changes: I think this will answer both questions and the implied PMF question as well. For internal FTE staff, this will be handle as a one off exception consistently (it’s really no one’s full-time job or responsibility). You may wish to speak with teams that offer professional services / SaaS including self-hosted where this infrastructure would be helpful. Their jobs are made easier with additional predicable / dependable infrastructure software (ie chat with (a) Twilio’s messaging team which remains the SendGrid acquisition, (b) related Red Hat / IBM) vs more work for an individual who is just doing this one-off. You may wish to consider a revenue share and/or white-labeling as they co-install the infrastructure for your business.