How do I look up a profile in Yahoo if I only have the email address?

Answer 1

Use the part of the e-mail address that comes before the @ symbol, type in http://profiles.yahoo.com/name like my e-mail is [e-mail] and to get my profile type http://profiles.yahoo.com/johnluke1169

Answer 2

doing a search from your 360, it gives you the option of searching email address to find if the person is a member of 360. It also gives you the option of looking up their Y! ID,(which is their Y! email addy) or by the first and/or last name.