How to disable mail send function for certain directadmin users?

Often wordpress or joomla sites those use nulled plugins causes to send lots of spam mails. I am limiting directadmin users to send x mails for a day. But I also want to know if it is possible to completely disable mail send function for these sites.

Two things I want to learn:
1. Is it possible to disable mail sending from any php codes? (with mail send() function or even smtp authantication - go to 2nd here)
2. Is it also possible to disable smtp service for these domains? And how please?

Thanks

1a) It depends on which php type you're using.
For CLI (mod_php) based php installs, it uses a global php.ini, so the disable_functions applies to all domains.
I believe all other php type (suPhp, php-fpm, fastcgi) will allow a per-User php.ini file, so you can add mail to the disable_functions list.
Let us know which php type you have and we can narrow that down for you.

1b) Another trick would be to add per-Email limits, if you've got exim.pl 16:
http://help.directadmin.com/item.php?id=514


2a) To disable smtp, you'd set a limit of 1 for the DA User, eg: where it's max of 1 emails per day. Setting it to 0 means unlimited. This is the same setting as in DA, per User.

2b) If you truely wanted 0, the /etc/exim.pl can be modified to suit your needs.. but you may want to chattr +i /etc/exim.pl if you do make any changes, to ensure your changes stick.

John

If I set limit to 1, and user tries to send lets say 100 mails, will 99 mails stuck in mail queue? If yes, I would have to completely disable mail send function.

Depends on how they're sent.

If they're sent via smtp, the 2nd email will throw a wrong password error (assuming exim.pl version 15+, 16 is current)

For command-line sends, the default would have them pile up in the queue, but they won't leave the box.
The solution for that, assuming you're running a user-privilege php type (suphp, mod_php+mod_ruid2, php-fpm, fastcgi), would be to setup a noexim group on /usr/sbin/exim, and chmod the binary to 4705, rather than 4755.
Info on that here (but for perl, so swap it around for exim): http://help.directadmin.com/item.php?id=490

John