All communication from NTA is online through your Registered Email id and Mobile number. In most cases Alternative Email Id is only used when the Registered Email id is not working. Most Candidates do not even furnish an Alternative Id. Now regarding NTA sending a soft copy of the admit card, when you download the admit card from the official email id, a soft copy is sent to the Registered Email id. And it is not sent to the Alternative Email Id. Because the Information Bulletin states that all kinds of communication between NTA and a Candidate is strictly online through Registered Email Id and Mobile Number. No where does it mention that the communication with an Alternative Email id is possible. So if your Registered Email Id is working, then the Alternative Email id will not be used for communication purposes. The reason why an Alternative email id details are asked is just in case the Primmary Email id isnt working. But if it is working or active, there is no reason why NTA would communicate on the Alternative Email Id.