I too haven't been able to access my yahoo. email with the web extensions for Thunderbird, but I actually went out to Yahoo and they have the setting to use for POPing their email to other email programs. It's very simple:
POP3 Server = pop.mail.yahoo.com.sg - Use SSL and port 995 SMTP Server = smtp.mail.yahoo.com.sg - use SSL and port 465, use authentication Login Name = Your email address without the @yahoo.com Password = Your Yahoo email password It's that simple and it works.
