Why does Sonic.net restrict incoming port 25?

[kennethporter]

Consider this solution:
https://www.postfix.org/STANDARD_CONFIG ... l#firewall
Use the transport map to log into a user on your home server (over port 587) and submit the mail for delivery to your mailboxes.

[dancingsnails]

Don't see how that helps. Port 587 is fine for accepting email from clients, but in order to receive email from other email servers, you need to open port 25 or tunnel in from somewhere that's listening on port 25. No way around that.

[kennethporter]

Correct. You need to set up a relay on a VPS that forwards the mail to your internal server over an authenticated 587 connection. A Linode can do that for $5/month and have plenty of capability left over for other things like a web server.