start up a junk email folder and it will send it all to this i your mailbox instead. I think you can set it to only except known address's in your inbox as well. Go to Mail in the top line, then preferences. Click on Junk in the top line of the box that appears and click on which ever bit about the junk you'd like to happen. It'll move it all to a junk folder. Simply don't reply to any of it and it'll slowly stop happening again.
I'm sure DH has done something else as well but can't check that till he gets home.