dear samhitha,

I want want to tell you that if you provide wrong email id which is not a valid email address then you can not able to finally submit your application form.so in this case you need to fill again your application form by using another mobile number and a correct email address.

On other hand if you already finally submitted your application form and  filled  the email id in your neet application form which is not accessible by you in future then it will not create any problem during counselling if you know your username and password completely.but in this case you can miss some messages sent by NTA because you can't access you registered e email. but you can also get messages by NTA in your registered mobile number.

hope this helps

if you have any doubts please ask.