1. Add the following lines to /etc/postfix/main.cf file:
  2. Create the file /etc/postfix/sasl_passwd with the following contents:
  3. Restrict permissions on the postfix file:
  4. Hash the file into a .db that Postfix will read:
  5. Change the owner of the sasl_passwd to the postfix user:
  6. Reload postfix: