import re


def validateEmailAddress(address):
    """
    Determines whether a string is a valid email address.

    This implements the grammar from 4.10.5.1.5 of the HTML Standard.

    :param address: The string to test.
    :type address: str
    :rtype: bool
    """
    # https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
    return re.match(
        r'^[a-zA-Z0-9.!#$%&\'*+/=?^_`{|}~-]+'
        r'@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?'
        r'(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$',
        address
    ) is not None