ask them to register at passport.net .. using whatever email address they currently use, it doesn't have to be hotmail... but, web based email addresses are better for registering with because thos address's are unlikely to change.
if they use hotmail already, ask them to sign up using their hotmail address if they use gmail .. ask them to sign up using their gmail address.
if they use gmail .. ask them to sign up using their gmail address. 
