You don't have to switch to gmail, you can pretty reliably switch to a myriad of service providers. You could even solely switch your SMTP server to something hosted and retain message storage on your end if you wanted.
It has become very difficult / unwise to host your own SMTP server, though, but that's been true for ages now. Gmail's marketshare is going to make that veeeery obvious, but it really has been a bad idea for the better part of a decade, at least.
It is a bad idea to host your own SMTP, but only because you need to keep on top of maintaining it. Most of that effort is the same if you have one user or a million, so it is more efficient to outsource that maintenance. However if you are willing to pay the price in time there is no reason you shouldn't be able to maintain your own server.
I use fastmail. They have humans that respond quickly when I have a problem (twice in 10 years)
Difficult to host smtp?! That's absolutely not true and has never been true. It's difficult to configure and set up in the first place but after that it's just updating. Source: personal experience for decades.
I though the issue was with getting your mails accepted. Even gmail has no problem sending email to a server that isn't properly set up as long as it is willing to accept.
Can you mention (or link to) situations where gmail refuses to send mails to another domain?
But it's not just postfix or sendmail you need to configure correctly and then put apt-get update/upgrade -y in cron to avoid the damage caused by making a mistake or falling asleep at the wheel. Casual self-hosters have other vectors of attack to mitigate, for example making sure sasl or whatever they may be using for imaps auth is solid, that passwords are strong and routinely changed, that php is also tight and so on. The stakes are relatively high, the efforts to compromise systems for this and other purposes are voluminous and incessant. So I'd say "it takes a village" to do this safely enough, not individual enthusiasts who cannot commit to administering a server diligently.
Any tips for somebody looking to move to my own smtp server? It's been on my mind a few months, and I want to move away from gmail to my own server or to another service, preferably one I pay for.
Surely someone has to run their own SMTP servers, or there won't be any SMTP servers. So how is it decided who can run SMTP servers and who can not, and is this a good method?
It has become very difficult / unwise to host your own SMTP server, though, but that's been true for ages now. Gmail's marketshare is going to make that veeeery obvious, but it really has been a bad idea for the better part of a decade, at least.