Resignation through email - date on which I updated in the portal as resignation date and extending my notice period by 2 days

Hi, I have sent a resignation through email and updated it in the resignation portal after two days. My organization is considering the date on which I updated in the portal as resignation date and extending my notice period by 2 days. Is this valid?

In my opinion, the management's decision seems correct. What prevented the poster to simultaneously updating the resignation portal?
When the employee sets the notice period as per the exit clause, it is always better to take into account the possible administrative delay.

My opinion is same in line of Mr Umakanthanji. The decision of management is right. It gives an impression that the resignation to be done using company portal is a mandatory rule of your company.
You can not held your HR people responsible for your own fault.