Questions on postfix

[Robert Schwalbe]

On 29/12/2023 15.28, Ubence Quevedo (thatrat) wrote:
>  That's just it, I am using mail from /opt/local/bin/:
>  uquevedo at ubence-mini-wired ~ % which mail
>  /opt/local/bin/mail
>
>  I shouldn't have to use a specific executable if it's attaching to a
>  standard port for a running serviceŠ?
>
>  Unless there's something configuration wise that I'm not seeing about
>  what port the postfix from MacPorts is doingŠ?

mail(1) does not connect to port 25 or 587 by default, if you wanted to
imply that. Unless you configured it differently, /opt/local/bin/mail
might probably still use /usr/sbin/sendmail, but I am not sure about that.

Depending on your macOS version, it already ships with postfix. The
relevant sockets are already bound by launchd to run the macOS postfix
installation on-demand. You won't see any running daemon processes as it
is only activated by launchd on an incoming connection as configured in
the /System/Library/LaunchDaemons/com.apple.postfix.master.plist file.
There is no way to get rid of this postfix setup unless you disable
System Integrity Protection (SIP).

If your intention is just to set up a relay over an external SMTP
server, you could just use the macOS provided postfix. I described such
a setup on my personal blog a while ago with a specific setup that was
required for macOS 10.12 Sierra, but the general instructions should
still apply today:

https://raimue.blog/2018/03/22/postfix-with-relayhost-over-stunnel-on-macos-10-12-sierra/

Rainer