Postfix canonical maps can be defined in 3 ways.
1. canonical_maps – rewrites the sender and recipient address
2. sender_canonical_maps – rewrites the sender address
3. recipient_canonical_maps – rewrites the recipient address
In main.cf, point the canonical_maps parameter to the canonical file and then add addresses that you would like to rewrite.
root# vim /etc/postfix/main.cf
# Add the following to your configuration file.
canonical_maps = hash:/etc/postfix/canonical
root# vim /etc/postfix/canonical
# address that would like to rewrite new address
root# postmap canonical && postfix reload