The ability and instructions vary based on the service provider, e-mail client, and/or the spam filter used. Assuming you are relying on Norton AntiSpam, part of NIS, you can do this by going into AntiSpam's control panel and configuring the block list. The block lists accepts both individual e-mail addresses and entire domains, treating all mail sent as spam.
Hope this helps,
I continually receive tips on penny stocks which do not offer a way to unsubscribe. I note that the sender changes only the name portion of their e-mail address. Is there a way I can block these e-mails using the domain name?? I use NSW and NIS 2006. TIA