You left out #3, someone reported what you said in PM.
Every network I have been on Admin wasn't able to read your PM's. Although this never stopped people from spreading the rumor. It is, however, possible for someone to edit their server.
There used to be a module for Unreal that did allow admins to read PM, I remember it caused a few nasty rows, and was decided that IF a server was running such a module it should be advertised in the server motd. However that was a while ago so I cannot verify if it is even available today. Thankfully I have always managed to stay away from Unreal all these years (apart from trying to figure out why it is so popular)
I forgot to mention I also seem to remember it being a 3rd party module.