Way to patronize someone trying to be self-sufficient.
Just because you read blog posts titled "DON'T HOST YOUR OWN MAIL", doesn't mean you shouldn't. People are scared of hosting their own mail servers because they
a) are told they shouldn't
b) don't understand SMTP.
I am all for decentralizing this hyper-centralized internet.
Sorry, I'm old enough to have come from the era of "DIY" mass emailing which transitioned (rightfully so) to using providers like Constant Contact/MailChimp. I've seen first hand the drawbacks of emailing thousands of people via your own SMTP server. Blacklists, legal threats, deliverability issues, proper unsubscribe, formatting etc. And this was early 00's when much of the legal framework around email marketing was either non-existent or weakly enforced.
Maybe I'm too old? Has email come around to the point where someone can host their own email and send out thousands of emails without having to deal with a mountain of headaches again? That would be sweet, maybe I can go back to telling clients it's okay to paste a massive list of email into their Outlook's BCC field? It would certainly save them some money. I still to this day hear from clients who send "small" mass emails wondering why their friends at AOL, or <insert your ISP here> didn't get the email.
Sorry but this is based on my direct, first hand experience with hundreds of small businesses doing this exact thing. I don't base my business model off of some random blog post, I base on years of experience and the lessons learned from getting burned.
I'm guessing that people who are criticizing you have mostly never run SMTP services for a decently sized ISP (something with its own AS number, big chunk of ARIN IP space, peering, etc).
I run my own smtpd for personal purposes, but if I were going to send outgoing customer-contact mails en masse, I certainly wouldn't do it through my personal perfectly-configured postfix system. Things like mailchimp fill a market niche.
We've been sending our email through our own servers since the early 00's. In my experience it's never been that bad if you are a good actor and follow best practices. Hell, even if you're a spammer and follow best practices you might still get through. But if you don't know what those are you will most likely go to the spam folder.
Regardless, hosting your own mail isn't the same thing as using outlook's BCC field.
I think email has come round to the point where you can, if you really want, run your own SMTP server and send out thousands of emails without having to deal with a mountain of headaches again, yes.
Tens or hundreds of thousands, maybe not. (And I'm assuming that this isn't email that the recipients are going to consider is spam.)
I think there are two major reasons for this improvement: DKIM basically works, and far fewer recipients are using email accounts provided by crappy ISPs.
I've provided "backyard" shared hosting for a handful of customers for about a decade, some of whom have mailing lists sizing up into a thousand recipients or so. I do encourage them to use proper mailing list services, but for the most part, shipping it all through my mail server works fine and there really aren't that many headaches.
Some basic good hygiene and some effort put into gently educating customers on how email works has gone a long way.
My biggest headache today is in receiving mail, not sending it. Because so many other people have followed advice like yours and jumped onto one crappy mail service or another, the originating network for an email is no longer a good signal for whether it's spam or not.
It indeed depends on personal circumstances. In my case my case sending mail through own SMTP server is not a problem.
Even if that would be a problem in future, you'd rather use one of SMTP PaaS (there are quite a few of them out there) instead of using fully integrated solution like Mail Chimp. I.e. you can use Mautic and connect it to Sendgrid or something like that. This way you have full ownership of mailing lists and newsletters content.
People are scared of hosting their own SMTP server because hosting an SMTP server is woefully insufficient for actually having mass mailings reliably delivered.
The hard part isn't actually sending the mail, the hard part is staying abreast of the already long and perpetually growing list of legitimacy signals you need to send to reassure understandably paranoid SMTP clients that they shouldn't mark your newsletter as spam. And you're not done even when the server is set up and configured properly; it doesn't take more than a handful of ignored complaints to start getting added to blacklists.
It's not difficult, per se, but it is a huge time investment for a service that centralized vendors can provide extremely cheaply because of economies of scale.
I'm all for moving toward decentralization too, but we're not going to get there from here if we don't understand and respect the incentives that lead people toward centralization in the first place.
Just because you read blog posts titled "DON'T HOST YOUR OWN MAIL", doesn't mean you shouldn't. People are scared of hosting their own mail servers because they a) are told they shouldn't b) don't understand SMTP.
I am all for decentralizing this hyper-centralized internet.