It's very very problematic. With all the spam, your mail server is not going to be trusted by any major providers. Their weak heuristics have no problem banning your 1 user mailserver, but they have gmail whitelisted to not ever ban them.
Agreed, this is the biggest barrier to running your own mailserver.
Even if you think deliverability is good for 95% of mail servers there's always some ISP that won't cater for you. So you're constantly having to be monitoring the logs to ensure your emails are being delivered.
Working professionally for a small company, which provide emails service for customers domains, i can say that this has never happen for us. not a single time.
Sometimes people get hacked, either because they pick a abc123 password (nowdays blocked by policy), or because a customer webserver CMS theme has not been updated in the last 2 years. When that happen, a few mail servers (mostly yahoo) has temp banned mails for a few hours. Mails still got delivered however.
So lesson to learn there is to not use passwords like abc123, and to actually update that 2 year old CMS theme. Or you don't combine webserver with webmail.
I agree with you. Most professional email services have much less aggressive blacklisting than single-user email services run by their single user.
In many years of running my own server, this was never a problem. I checked blacklists on a somewhat regular basis but was never in them. And people I sent mail to usually replied, which means they are either psychic or my mail got delivered. (The problem comes when you start sending spam, of course, which is what many people do get blacklisted for.)
The problems with running your own email server are spam and the time it takes to keep things running. All the other issues are trivially solved.
