def METHOD_NAME(email: str) -> None:
    if is_cross_realm_bot_email(email):
        if verbose:
            msg = email_reserved_for_system_bots_error(email)
        else:
            msg = _("Reserved for system bots.")
        deactivated = False
        errors[email] = (msg, deactivated)
        return
    existing_user_profile = user_dict.get(email.lower())
    if existing_user_profile is None:
        # HAPPY PATH!  Most people invite users that don't exist yet.
        return
    if existing_user_profile.is_mirror_dummy:
        if existing_user_profile.is_active:
            raise AssertionError("Mirror dummy user is already active!")
        return
    """
    Email has already been taken by a "normal" user.
    """
    deactivated = not existing_user_profile.is_active
    if existing_user_profile.is_active:
        if verbose:
            msg = _("{email} already has an account").format(email=email)
        else:
            msg = _("Already has an account.")
    else:
        msg = _("Account has been deactivated.")
    errors[email] = (msg, deactivated)