Relieving Letter From Current Employer

Dear learned friends,
I was working in a public company and tendered my resignation for better prospects. My notice period is 90 days and already more than 1 month has passed since I have served my resignation on email to HR.
However, they have not acknowledged the receipt of my reisgnation letter nor are they coming up with any date of my relieving. I wish to join my new employer in the next week and if not then my opportunity will be lost.
My question is what are the remedies/actions can I take against my current employer
Pleae guide me as I am too stressed. Thanks

Dear friend,
will you accept if the company is sending you an appointment order through email? Do you think it is valid without any signature of the authorised person of company?
Similarly, you would have give or send your resignation letter in hardcopy. This is the right way and then only you can ask the managment for further query/settlement.

Dear SIr,
thanks for your reply. However the HR of my company is not accepting hard copy of my resignation letter. What do I do?
Kindly guide for getting my dues and smooth relieving

Dear friend,
everything can be successfully solved if you talk amicabily with your hr persons. You talk to them in person.