I'm operating a Postfix server, and my local network has port 25 blocked. I've tried everything I can to in order to get port 25 unblocked - no dice.
Unlike this I don't want to proxy my data. (Haven't found a good way to do it since I don't have external servers) I'd rather just send stuff over port 587 instead of 25 - since 587 isn't blocked for some reason.
How exactly do I go about setting my postfix config to send emails on port 587? I'm fairly sure the hosts I'll be sending to support port 587. An alternative could be proxying if it still sends from the email account on my server, is free, and doesn't use OAuth2 (I'm specifically setting this up because of misconfiguration of platforms like Outlook, and Gmail demanding OAuth2).
I'd like to note that I'm using Ubuntu 20.04 LTS as my server base - so CentOS/RHEL tricks won't work.