Zero entries in bounced email list

Thanks for the reply. I have configured the SES as mentioned in the link. But regarding the reply by email address, which one should I use? domain or subdomain.

Assume, my domain is example.com and I have verified mail.example.com at SES for email. So I have to use,

replies+%{reply_key}@example.com or
replies+%{reply_key}@mail.example.com?