I'm surprised by how many people think mail is an impossibly hard problem. There some things about mail that are stupid; the core protocols are old and it shows

I'm surprised by how many people think mail is an impossibly hard problem. There some things about mail that are stupid; the core protocols are old and it shows. But, once things are working, you can leave it alone for years (aside from regular software updates) without trouble. I have. I've never not run my own mail servers (and often for several other people/companies/projects, as well) in the past 20 years. I used to consider myself an expert on the topic, but it's required so little of my time/thought in the past several years that I've forgotten most of that expertise. I think what I'm trying to say is that it's not harder than it used to be (though some problems, like spam and security requirements for safety, have gotten worse in absolute terms). With modern tools and packaging on modern Linux distributions, you can be up and running pretty quickly. My company ships a turn-key solution as part of Virtualmin, but you can build something similar without that in an afternoon or two if you're reasonably Linux-savvy and have some notion of how all the pieces fit together (maybe a couple extra afternoons if you don't know the basics; DKIM and SPF can be tricky, since you also have to know or learn you some DNS). It's harder than a web server or DNS server, but not something you should flee in terror from. Admittedly, it's gotten cheaper in recent years to outsource it...and with microservice-based architectures, maybe it makes more sense to have some other API than SMTP (though SMTP is very easy to use from every language I've ever worked in). But, there are problems and complexities with outsourcing, as well.