I thought there used to be a report to moderator link on personal messages - but I can't find it now.
I received a message from someone calling himself jadcolla on 19 Nov asking me to beta test something. I assumed it was genuine and replied saying "no thanks"
This evening I received another identical message from the same person so I assume it is SPAM.
...R
No idea, sorry.
However, oddly enough, I have had a couple of messages from jadcolla too.
The message sounded genuine, it started:
I read some of your posts and I like the way you think… and you are exactly the type of people we are looking to test out ...
However "I like the way you think" could probably be written to anyone without them becoming suspicious.
I wonder if jadcolla likes the way anyone else thinks? I notice he has no posts to his name, so he may have joined just to spam people by PM.
I just got a second, identical, message from him/her so I banned him/her/it.
Apparently he/she/it still likes the way I think, but has trouble remembering that s/he told me the same thing yesterday.
I wonder if they still llike the way you think after banning them. 
Exactly the same as mine.
...R