multiple E-mail addresses for forum

How about multiple E-mail addresses in the forum for user accounts so they can be informed of new posts Eg at work and home. You can set one of them as a default address that important registration info and so on can be sent to. This saves users registering two times. One for work and one for home ect, Also helping visitors having to keep logging back to check for posts because the notification is being posted to opposite e-mail accounts.