I've just had a spam private message sent to my test account on the forum. The message reads along the lines of 'hi, I'm new here....' and contains a link in the signature and importantly the user has zero public posts. It appears as though this spammer has been posting private messages for about half a year now.
If you receive a message that looks suspicious, please use the 'report PM' button to report the message, screenshot coming up...!:
(open the message in question and you should see the triangular 'report PM' button as in the picture above ^)
Alternatively you can contact me or any of the mods to report it and I/we will look into it.