The main yahoo.com IDP will asserts emails in all of the domains listed below and Google operates the email services of those domains. Yahoo.co.jp is a special case because Yahoo Japan runs their own OpenID endpoint as opposed to using the one run by yahoo.com.
@yahoo.com
@rocketmail.com
@ymail.com
@yahoo.com.ar
@y7mail.com
@yahoo.com.au
@yahoo.bg
@yahoo.com.br
@yahoo.ca
@yahoo.cl
@yahoo.com.cn
@yahoo.cn
@yahoo.com.co
@yahoo.de
@yahoo.dk
@yahoo.es
@yahoo.fr
@yahoo.gr
@yahoo.com.hk
@yahoo.co.id
@yahoo.ie
@yahoo.in
@yahoo.co.in
@yahoo.it
@yahoo.co.kr
@yahoo.lt
@yahoo.lv
@yahoo.com.mx
@yahoo.com.my
@yahoo.no
@yahoo.co.nz
@yahoo.com.pe
@yahoo.com.ph
@yahoo.com.pk
@yahoo.pl
@yahoo.ro
@yahoo.se
@yahoo.com.sg
@yahoo.co.th
@yahoo.com.tr
@kimo.com
@yahoo.com.tw
@yahoo.ua
@yahoo.co.uk
@yahoo.com.ve
@yahoo.com.vn
@bellsouth.net
@ameritech.net
@att.net
@attworld.com
@flash.net
@nvbell.net
@pacbell.net
@prodigy.net
@sbcglobal.net
@snet.net
@swbell.net
@wans.net
@btinternet.com
@btopenworld.com
@talk21.com
@rogers.com
@nl.rogers.com
@demobroadband.com
@xtra.co.nz
@verizon.net