Sendmail keep a user from send message

Hello,

i have a problem with my sendmail, i want' to keep a user from sending mail, how can i process ?
My user is titi, and i don't want' that titi can't send mail via sendmail is it possible ?

thnak a lot

Here is something that might work, but I'm not gonna try it. So no money-back guarantees on this one...

Create a group called "nomail" or something and put titi in it.

Then do:
chgrp nomail /usr/lib/sendmail
chmod 4705 /usr/lib/sendmail