class MailGW(mailgw.MailGW): 
    ''' derives basic mail gateway implementation from the standard module, 
        with any specific extensions 
    ''' 
    def hasPermissions(self, author, classname, nodeid):
        return (mailgw.MailGW.hasPermissions(self, author, classname, nodeid) or
                (self.db.security.hasPermission('CreateOrReplyToSelf', author, classname) and
                 nodeid is None) or
                (self.db.security.hasPermission('CreateOrReplyToSelf', author, classname)
                 and replyingToSelf(self.db, classname, nodeid, author)))

def replyingToSelf(db, classname, nodeid, userid):
    node = db.getnode(classname, nodeid)
    return node['creator'] == userid