Email Blacklist

I just would like to know how to block e-mails from a certain e-mail address? Not inclucing bulk mail.

I am a paying AT&T customer. I have made several attempts to register and send and resend my confirmation email from GSN. Its not showing up in my pop3 mail, on webmail, or even in the bulk/spam folder. Are they blocking my email in some way which prevents me from even seeing it in bulk mail? I pay good money for this AT&T account and I expect them to deliver my mail. Its my decision whether to mark it as spam or accept it, correct? Anyone else having this problem, and if so, what have you done about it?
First answer did not appear to solve the problem, but I don’t know the full address of the incoming mail, just that its @gsn.com. I put *.*@gsn.com and @gsn.com in addy book. It won’t take just gsn.com. However that should be sufficient syntax to allow email to come through from that domain, since its sufficient syntax on the block list.

Regardless, I appreciate the answer, but it still doesn’t explain why, with spam filters off and pop3 set to deliver everything including bulk (with *bulk* prefix), I still don’t see any trace of the several incoming emails I know have been sent. If I am paying for this account I should be getting the mail I am paying to receive. What I am trying to determine is if Yahoo is blocking my mail at the domain level and not even allowing me the chance to decide if I want it. That might be ok on free disposable email account, but it is unacceptable to me on an account I am paying for. Question still open… any more thoughts?

My Trash collector claimes to have emailed me my bill but it never arrived in my In Box. They think it may have been stopped by a spam blocker. How can I enter thier address as NOT SPAM directly. Or how can I search the 1000+ blocked mails for thier letter?

In other words, the computer won’t let it get into my bulk mail but it gets into my e-mail. why doesn’t the spam guard stop it from getting into my email?