My team applied from Kanpur Region for ICPC and we got a little late in sending the postal mail regarding transaction id of payment details to Kanpur site. Still we have 2 days for the post. I hope it will reach, but in case it gets delayed anyhow, please make an exemption.
Firstly, this should be mailed to the concerned authority (whose contact details are given under website) and not posted here- they dont check codechef discuss.
Secondly, dates are extended till 19th afaik if you check the website.