I seems to work for me, an alternative is to use the POP/Formward option in Yahoo Mail and use the Mozilla Mail client to read it. If Moz won't get Yahoo mail to do this, yoiks, use IE to set it up, and then Mozilla Mail to read it.
The POP and SMTP addresses are:
pop.mail.yahoo.com
smtp.mail.yahoo.com
You have to configure it with Yahoo mail to get POP access by agreeing to them sending you more spam.