FinderDestTable::getMailUserId

static function getMailUserId($code)
{
	$userId = [];
	$result = [];

	if (!is_array($code))
	{
		$code = [$code];
	}

	foreach ($code as $val)
	{
		if (preg_match('/^U(d+)$/', $val, $matches))
		{
			$userId[] = $matches[1];
		}
	}

	if (!empty($userId))
	{
		$res = BitrixMainUserTable::getList(
			[
				'order' => [],
				'filter' => [
					"ID" => $userId,
					"=EXTERNAL_AUTH_ID" => 'email'
				],
				'select' => ["ID"]
			]
		);

		while ($user = $res->fetch())
		{
			$result[] = $user["ID"];
		}
	}

	return $result;
}