Generally residential connections block outbound port 25, because of the spam issues that were caused by compromised computers in decades passed. Also, I ran a

Generally residential connections block outbound port 25, because of the spam issues that were caused by compromised computers in decades passed. Also, I ran an email server at home when I was a teenager, the availability of the server was less than I wanted, so I've had to move that email service elsewhere. I suspect relatively average people would have a very hard time operating a satisfactory email service at home even if all of the SMTP stuff is perfectly reliable and foolproof.