# Allow user to send email without smtp authentication Create a plain text file: `/etc/postfix/accepted_unauth_senders`, list all users' email addresses which are allowed to send email without smtp authentication. We use user email address `user@example.com` for example: ``` user@example.com OK ``` It's ok to use IP address instead like below: > For more allowed sender format, please check Postfix manual page: [access(5)](http://www.postfix.org/access.5.html). ``` 192.168.1.1 OK 192.168.2 OK 172.16 OK ``` Create hash db file with `postmap` command: ``` # postmap hash:/etc/postfix/accepted_unauth_senders ``` Modify Postfix config file `/etc/postfix/main.cf` to use this text file: ``` smtpd_sender_restrictions = check_sender_access hash:/etc/postfix/accepted_unauth_senders, [...OTHER RESTRICTIONS HERE...] ``` Restart/reload postfix to make it work: ``` # /etc/init.d/postfix restart ```