Marking spam emails in a Yahoo Mail account using the spam button appears to be  ineffective. One will continue to receive similar and even identical email spam. Although the Yahoo spam filter is effective for the majority of spam, apparently the spam button contributes to a general spam filter algorithm and not to a user specific spam filter as is the case with gmail.

One way to help filter out the spam on a Yahoo Mail account is to filter all messages not containing your email address in the recipient field.