HDFC Bank — otp on email is not received

I have to reset my net-banking pin. There are 2 options :

1) registered number + debit card — i can't use this because i have the debit card, but i have not created it's otp (By that green otp method)

2) registered number + e-mail : now the problem is 3 digit otp comes to the registered number but the email never arrives, i dunno why is it happening.

Ps: this used to work earlier, i have had reset my ipin by this method twice earlier.