def __getaddr(self, keyword, arg):
        address = None
        keylen = len(keyword)
        if arg[:keylen].upper() == keyword:
            address = arg[keylen:].strip()
            if not address:
                pass
            elif address[0] == '<' and address[-1] == '>' and address != '<>':
                # Addresses can be in the form <person@dom.com> but watch out
                # for null address, e.g. <>
                address = address[1:-1]
        return address