lots of other games do it so why not make it so a player you can not use shout or yell until after level 10 or even 15 and cant send tells until after you have passed the main 3 dungeons or unless person is on friends list.
Secondly, the biggest thing on our server which is obvious RMT activity, since beta the same level 1 npc sits at mail moogles in main cities normally and if targeted won't get in activity disconnected. Track their mail and ban them accounts. Members of our FC have watched the same npc 24/7 sit at various city mail moogles since official release. Trace their mail!!