Feature Request. Time Out Delay on Private Messages for Server

Bot raiding is getting out of hand and and the while there is bots that can deal with on the chat side there is nothing you can do on the Private message side other than disable private messages for that server which I think isn't really the best option for anyone and doesn't really promote the growth of a community. 

I am purposing a setting an admin or owner can enable that is similar to time delay in chat that will enable users to PM when they are members for a X amount of time. Exceptions are people who are in other servers together or people on friends list..