You can modify the server and send the message to the bit bucket. This can be quite misleading to users. The servers I see use a
bounce-xxxxxx@ address for outgoing messsages.
Setup the correct DNS entries including SPF.
You are required by the RFCs to have a working postmaster address, otherwise some sites will block your server. Also if you do have a problem with your server other administrators won't be able to notify you of the problem. I see lots of misconfigured sites which will have problems delivering mail that don't have a postmaster account. They will continue to have failing deliveries.
You may want to deliver your bounce messages to a program which handles tracking the bounce messages.
Messages are bounced during the connection to the servers so you should not generate any bounce spam. The only vector for this is open relays, and the bounce will be sourced from them on other servers.