Confirmation Letter not Accepted - Can I leave the job as per Probation period Terms & Conditions?

Dear Umakanthan Sir, HR Experts, I had been given Confirmation Letter after 12 months instead of 6 months. I received my Confirmation Letter Scanned copy on mail, as it was Lockdown Period. Now, I have NOT given my Acceptance to the HR team or to my manager, neither in the mail nor in writing, and they too have forgotten to get my acceptance.
Now if I Resign, will I have to serve 3 months notice as per Rule for Employees who are confirmed in the company. OR, Can I leave the job as per Probation period Terms & Conditions (can leave within 15 - 20 days notice period).

You need to abide by the rules in force in your company. Please refer to the separation clause
mentioned in your Offer of Appointment. Even though you have not accepted the mail communication of confirming your services with the company, it is deemed to have been
accepted by you, as you have received the e-mail. Hence, the clause of separation, on confirmation, shall be applicable to you.

Thanks a lot Sir for your proper guidance.
Can I act ignorant that I am not aware about any such mail received by me about my confirmation, in order to negotiate reduction of my Notice Period from 3 months to 45 days.
I am doing all this only because once I resign, I do not want to stay long , as my Manager has always demotivated me throughout my tenure. She is a demotivating person not only for me, but for employees who have been in the company for many years also.
Regards,
Abhishek

Dear Sir,
You are liable to follow the terms and conditions which is mentioned in your confirmation letter followed by the appointment order because you had received the confirmation letter through mail. So they have solid proof for given the order. Still you didn't refused that email that is enough for acceptance.
Mani.K