The main reason for not receiving your OTP could be

1. The email address you provided is not correct. To correct this, you have to check that the email address is correct.
2. Your mailbox is full and cannot receive any more emails. You have to delete old emails to allow new emails into your mailbox
3. The email was sent to your spam/junk folder. Open your spam/junk folder to check if you can see a Quab Express email there.