"""The one rule for a usable e-mail address. No Django imports: the config reads it at startup."""

import re

_ADDRESS = re.compile(r"^[^@\s<>,;\"()\[\]\\]+@[^@\s<>,;\"()\[\]\\]+\.[^@\s<>,;\"()\[\]\\]+$")


def is_valid_address(value: str) -> bool:
    return len(value) <= 254 and bool(_ADDRESS.match(value))