Is email resignation valid under government service rules?

Sir, I am a govt employee trying to resign from the service. I submitted my notice of resignation through EMail in January, 2024. There was absolute silence on the part of the department for 6 months. In July, when I sent a reminder, they created a new story that resignation notice submitted through email is not acceptable and that I have to submit hard copy and serve notice afresh after submitting hard copy. In view of the aforesaid, can you guide me as to whether there is any provision in service rule/conduct rules/judgment that resignation notice has to be mandatorily in hard copy or that email would not be accepted. Conversely, if there is any rule/judgment whereby it has been held that EMail would also be acceptable, kindly let me know the specific provisions. With Utmost Thanks and deep gratitude, Dr. Sabyasachi Paul