'@returns: When a C{memo} is passed in this will raise a
L{smtp.SMTPBadRcpt} exception, otherwise a boolean
indicating if the C{user} and string version of
L{self.address} are equal or not.
@rtype: C{bool}'

def exists(self, user, memo=None):

    if memo:
        raise mail.smtp.SMTPBadRcpt('ham')
    return (lambda : (user == str(self.address)))
