Caused by the massive abuse of the PM system in the past, the Coppermine dev team has decided to pull the break and disable sending of personal messages for all regular users on the Coppermine forum. Subsequently, regular users can only receive PMs from members of privileged groups, but they can not send any PMs. This is sad for the few users who used the PM feature for what it was designed to be used for. However, the vast majority of PMs sent (of course they were send by a minority of users who misbehaved) used to be crap.
We're sorry for those who got used to the feature and who have used it in the past for legitimate purposes. Keep in mind that there is no individual support by mail or PM anyway.
For those of you who wonder "how do I contact the developers/supporters of coppermine then?", the answer is: not at all. We do not want to be contacted privately in the first place. If you have something to say or report or have a question, post on the corresponding support board. If we need to be contacted privately, we'll send you a message that explains how to accomplish that.