This has legal implications, so if you are not submitting in person and receiving the acknowledgment, you should send the hard copy duly signed, in duplicate, with a request to return one copy duly acknowledged, and send it by registered post with acknowledgment due. Even if you send the communication through the official email ID, ensure that a confirmation copy, in print and signed by you, should be posted with proof of posting. This is for the simple reason that unsigned communication, particularly in such important matters, sometimes will not be treated seriously.
Regards,
Kumar S.
BG.