Views:
Please follow the steps below:
  1. Go to Postfix and open the “opt/trend/imss/postfix/etc/postfix/canonical”
  2. Add new lines with email mappings in following format:
            john@example.com           john.doe@example.org
  1. Save your changes
  2. Go to Postfix and open the “opt/trend/imss/postfix/etc/postfix/main.cf”
  3. Point the canonical_maps parameter to the canonical file with a new line:​​​
canonical_maps = hash: opt/trend/imss/postfix/etc/postfix/canonical
  1. Save your changes
  2. Execute postmap against canonical file and reload Postfix so that it recognizes changes to main.cf:
#postmap opt/trend/imss/postfix/etc/postfix/canonical
#postfix reload

This configuration will rewrite "john@example.com" sender to " jane.doe@example.org".
 
Reference: https://www.postfix.org/ADDRESS_REWRITING_README.html#canonical