CCrmEMail::FindUserIDByEmail

static function FindUserIDByEmail($email)
{
	$email = trim(strval($email));
	if($email === '')
	{
		return 0;
	}

	$dbUsers = CUser::GetList(
		'ID',
		'ASC',
		array('=EMAIL' => $email),
		array(
			'FIELDS' => array('ID'),
			'NAV_PARAMS' => array('nTopCount' => 1)
		)
	);

	$arUser = $dbUsers ? $dbUsers->Fetch() : null;
	return $arUser ? intval($arUser['ID']) : 0;
}