Forgot password won't work

My forgot password thing is not working properly. It is giving me this error
Mailbox unavailable. The server response was: <andrewsmd87@gmail.com> No such user here Server Error in '/' Application. Mailbox unavailable. The server response was: <email@domain.com> No such user here

The problem is, in my web.config file I have the settings


<mailSettings>
            <smtp from="admin@site.com">
                <network host="mail.server.com" port="25" />
            </smtp>
        </mailSettings>
Why is it not using the admin@site.com to send? Thanks,