Blocking an e-mailer

I have a friend whose husband shares the same e-mail address. He continually sends me objectionable, crude jokes, pics, etc. I've asked him to stop, sent him a reminder to use my DH's e-mail if he feels he has to fwd this junk, and I've threatened to block their e-mail address.....he continues to send it...to me. If I block him, I want him to know I've done so and will send last e-mail to them....but I want to know....will his e-mails bounce back to him, as I hope they will? This isn't just an occasional one, he sends 6 to 10 a day. I've told his wife I'm not comfortable with what he sends, and she said she'd have him stop it. Since they share the address, I never know which of them is sending when I open mail. I've long since stopped opening anything from them with an attachment, and asked them not to send them, but he still does. We've all been friends for nearly 35 years, and I hate to lose touch with her....but I can't understand her tolerating this.