...Most of this old members that are messaging newbies in other to scam them has already been given negative feedback by DT members in this forum, so when you see a PM from old forum members, what you should do is to check their feedback and from there feedback you will know the kind of person they are...
It doesn't matter if an old forum participant or a newcomer wrote to you, if the proposal concerns a financial issue, you should simply ignore this message. If this is a really good offer, then it will usually be publicly posted on the forum, rather than being sent out via private messages to unknown forum participants.