Notice Period Confusion: Can My Employer Enforce a Longer Notice Without Agreement?

I am in a situation. My organization is a small organization, and I have signed a one-month notice period with them. But one fine day, all employees received an email from HR stating that from now onwards, all employees have to give a three-month notice. If anyone has any concerns, they should reply to this email.

Now, what is the actual enforceable notice period for me? Out of fear, everyone is now giving a three-month notice; otherwise, they are not receiving their full and final amount (as per policy, they only give half salary during the notice period) and are not receiving an experience letter.

Please help with suggestions. It is even difficult for us to fight significant legal battles with the employer.

Dear Friend,

In this case, which clause is mentioned in your appointment letter during your joining that will be admissible rather than mail documents. I suggest you discuss with your HR, mentioning the clause in your appointment letter signed between you and management during your joining. If, despite this, they appoint their own arbitrators, then please write an email to management stating that you will seek legal help if management doesn't address this issue.

Thank you.