yes, but it's a bit hidden. I've never known why!
Go to "My Messages", then go to "Preferences" and "Manage Rules". (Or alternatively,
just click here)
Click on "Add new rule" in the bottom right
Fill out this form like this, but change
"the_spammers_name" to the username of the guy you want to block
Check the description in the bottom, does it say what you want it to do?
Just hit save rule:
This should delete all the messages coming from the username you supplied. I haven't tested if this works, but I imagine it does!
VC-MP: 
