Found good indications to effectively enable sending mail from the mac! (essential, e.g., fo running moodle and other cms which e.g. use e-mail for confirming registered users).
It is a post published by Anders. I had some problems though: I had to modify the relayhost line. Instead of being:
it had to be
Also, when I do a
sudo postfix reload
I gate an annoying message:
postfix/postfix-script: fatal: the Postfix mail system is not running
however, everything works…