Based on contract of employment it is usually written that you need to give notice when resign, so technically it is okay. Contract did not say that a letter of acceptance has to be given or approval is required. You just need to make sure that HR calculates all the outstanding leave and money that owe to you on your last day. For reason of peaceful departure, and not burn bridges, communication with HR is still important. Cautious at all times as to play safe it's advisable to give a copy of your resignation letter to HR Recruitment Manager and acknowledge receipt of the same. Double check the date of received and confirmation with his/her official designation chop. To practice and adhere to the code of ethics and aware that management has tight schedule also to avoid any miscommunication / delayed in your salary / anything that need to take into consideration. Employees with an outstanding attitude should act with integrity, comply with laws, maintain a professional work environment, comply with company policies and to practice professionalism until last date of employment thereafter to maintain any Private & Confidential agreement which agreed during employment. A+ and outstanding attitude carried weight to your next career pathway as a shield to serve as a valuable reference. All the best for your future endeavours.