I was reading through the advertisement forums, and I noticed that even though we have rules that says you should not post "email sent" " PM sent" etc.... Users are still doing it.

Of course, lots of times they are just newbies who forgot to read the rules, and had the urge to proclaim their accomplishments (of having sent a PM). I reckon that perhaps by including a line at the post screen, such as "Don't post 'email sent'" so that the user would realize that it is not allowed.

Perhaps even better would be to generalize this remind to increase some common things such as,

"Don't post useless, smillie posts"
"Please post advertisement only in advertisement forums"
"Don't be rude to other users; or else you will be banned"

and other examples, to remind users about posting in a community.

Peter