What meansure do you guys use to prevent someone who is customer and who is NOT customer sending out spam using nobody?

Greetings:

Consider installing http://www.enderunix.org/spamguard/

While it no longer helps against a lot of spam activity that involves people changing their from address; it can catch customers spamming; and it can help catch or lead to catching vulnerable formmail scripts.

Thank you.

Yes. that's what I am looking for.

There is a customer uploaded a script to spam, even we catch it after 5 hours, but damage has been done.

You can disable the nobody account from sending ANY email outside of the server.

In WHM go to Tweak Settings and you will see an option to "Prevent the user 'nobody' from sending out mail to remote addresses (php and cgi scripts generally run as nobody if you are not using phpsuexec and suexec respectively.)"

Check this to make it active and then the nobody account will not be able to send out email any more.

some program such as phpBB need to send it as nobody.

how do i let those emails go?

you can use smtp in phpbb