I set up my Postfix with in- and outgoing spamchecks/quota. Also, I disallow the port 25 for regular users and force them to authenticate themselves via tls on the submission ports.
My problem is, that all this can easily be bypassed with the php mail() function. Does somebody know how I could at least force php to send his mail through postfix so all mails will be spamchecked (and dkim-signed)? Even better would be the possibility to force the authentication (i.e. via user/pass in the users php.ini).
Thank you in advance.