Your own email server requires near 100% uptime or you risk not receiving critical emails. If a remote email server is trying to contact your email server and it can't it's only going to retry a few times and then give up. Hosting this yourself sounds great until you realize high uptime is not cheap and requires constant attention.

Setting it up securely can be difficult depending on your understanding of server infrastructure as well as protocols like DNS. You need to set up SPF, DKIM, DMARC, etc in order to prevent someone from faking an email from your server.

Of course, federated email does not use SPF/DKIM/DMARC because the whole point is that someone from another server could use your server to send an email (hence the federation). Open email servers were common 20 years ago but very rare today. That makes setup easier, but the main caveat is that most known non-federated email servers will reject email from servers that don't have SPF/DKIM/DMARC because they generally end up being havens for bots and spam since there is no verification or authenticity of the sender.

As someone who self hosts a lot of things, I would never self host my email. If i did I would be paying for two boxes in different parts of the world on different ISPs to provide that uptime. I would definitely set it up securely and not as a federated server otherwise it would be practically unusable for day to day emails.

@DidacticDumbass
Yes I run my own mailserver. I have done it for the last 15 years or so.

I'm also running my own Friendica instance.

Just take a look at https://docs.mailcow.email/

This runs from a small box with everything included. It gives you all the tools and config needed for running a secure and feature rich email service. Webmail, some sort of exchange emulation, webcalender on top of a solid postfix/dovecot install with rspamd as spam filter. Everything is configurable via a nice web UI.

After 15y running my own mail service and editing a lot of config files, I use this piece of free and open software and find it very good. All you need is a box somewhere in the internet. Running from a homelab will instantly fail, expect you have a static ip.

I have run my own email server, and have worked in the commercial web hosting sector.

Honestly, I wouldn't run your own email except as a side project.

It's certainly possible and all the tools are available and easy enough to use, but email in general is a rough combo of super old, and a "big target".

The super old part means that a lot of things that we might consider standard for a modern federated system just aren't there for email. Security is profoundly lacking, and if something gets dropped because of an update, or your computer crashed, there's no guarantee that the system will find a way to get it to you, and the sender might not even know it didn't get to you.

Security wise, you basically have to set everything up correctly all at once, or some system somewhere between you and the recipient will just throw the messages away, and they may or may not tell you.
They do this because all the tools are old, crufty and there's a lot of good exploits that misconfiguration leaves open that automated tools can use to send spam.

Be sure to keep your computer fully patched, and install a malware scanner, even on Linux.

Ultimately, I wouldn't bother running one because the ratio of reward to work is just off for me. I would recommend setting something up for an afternoon though, just so you can see how the pieces work, and get to send yourself an email and know what steps it took.

It's bad out there when it comes to hosting your own email server. This blog post shows somebody's experience in detail, and it's worth reading. https://cfenollosa.com/blog/after-self-hosting-my-email-for-twenty-three-years-i-have-thrown-in-the-towel-the-oligopoly-has-won.html

It's all so sad.

I run my own Mailserver on a vps with mailcow dockerized. Was a real pain to set up, even through it mostly works right now.

DNS stuff isn't just some A or AAAA records, also txt stuff reverse DNS and much more. As the others said, that's completely impossible with a regular ISP.

I'm on some dumb blacklist because my IP is obviously in the IP range of my hosting provider, and some lists generally block all vps ranges.

Now imagine the following: your bank wants to contact you and your primary mail is selfhosted, for some reason they block your IP (yes outgoing blocks, those idiots) and you don't get some real important mail. Or your server is down for maintenance, certificate issues, so on.

The best solution is most probably letting a professional email holster take care of your domain, for email at least. Protonmail offers that but the problem I have with them is that they don't allow a regular login through thunderbird, restricted to their own software.

Not worth the hassle - best compromise is to get your own domain but get something like fastmail to host it.

If they turn sour you can move your domain to another mail host.