How to find emails sent,deferred, bounced with logs on exim mail server

Postfix relayhost doesn't send local mail to the relayhost normally:

From postfix.org:

relayhost (default: empty)

The next-hop destination of non-local mail; overrides non-local domains in recipient addresses. This information is overruled with relay_transport, sender_dependent_default_transport_maps, default_transport, sender_dependent_relayhost_maps and with the transport(5) table.

So if it is happenning, it is because your local mail is not identified as local. You need to include your local domain in mydestination = config line. I see you have the ec2-....amazonaws.com there but probably you have defined a local domain different than this one for your LAN. If you don't have defined a local domain, I think (needs testing) if you only add 127.0.0.1 localhost.localdomain localhost in your etc/hosts file and add localhost.localdomain to mydestination= it should be sufficient.

A closer look at the basic access controls available should help you out; just specify the appropriate access map in smtpd_recipient_restrictions that denies access to those domains:

smtpd_recipient_restrictions = check_recipient_access hash:/etc/postfix/blacklisted_domains, permit_mynetworks, reject_unauth_destination, permit

and in /etc/postfix/blacklisted_domains:

bad.domain1    REJECT
bad.domain2    REJECT
baduser@bad.domain3    REJECT

Don't forget to postmap that file.