I have purchased many times from snapdeal, and have always received the products on the mentioned date without any delay, Everytime I decide to buy a product I would check for it first in snapdeal products site and then move on to other e-commerce websites.
I recently bought Blackberyy mobile, and as mentioned the delivered product was sealed and the blackberry box had the note about 18 months company warranty as well. I always opt for Cash on Delivery method only. I received the product through firstflight couriers.