Notice period in rental agreement

My rent agreement says either party has the option to terminate this agreement by giving 1 month prior notice in writing. My rent payment cycle starts on 1st of every month . I contacted my landlord on 1st of Oct and informed him that I want to vacate the flat.in additio I messaged him on whatsapp on second of Oct as well, By Oct third I couriered him the notice letter explaining that I'm going to vacate the house within 1 month (the house will be vacated untill 31 of Oct) . Accordingly I have paid him the current rent for Oct . Now he is insisting that I have to pay him rent for the next month also (full rent of Nov), because he states that he has received the couriered notice on his hand Oct 11 and he believes that one month notice will be executed from the date when he collects the letter from postman. Hence the I have to pay the full rent for Nov as the the date of received letter is Nov 11. Please let me know your views. Regards