Some email providers mark general booking emails, such as those sent by iHeartDR, as “spam” and deliver them to your spam folder. Please check there for any replies. If you have your spam filter set on certain privacy settings, only emails from addresses that you have in your address list will go into your inbox.
Any other emails – including replies from websites you have used for bookings – will go into your spam folder. Some email service providers automatically delete emails in your spam folder after a short time.