In order to configure postfix as a SMTP mail server in fedora, please follow this process
Process
1. Execute the next command from the console to install postfix
[abernal@sandbox ~]$ sudo dnf install postfix
2. Execute the next command to install mailx
[abernal@sandbox ~]$ sudo dnf install mailx
3. Check that port 587 is not bloqued by a firewall (default firewall : iptables)
[abernal@sandbox ~]$ sudo iptables -L | grep 587
4. Open the postfix master.cf file
[abernal@sandbox ~]$ sudo vim /etc/postfix/master.cf
5. Uncomment the "submission" line and all the overwrites you find under it. The overwrites start with a few spaces and the character -o
submission inet n - n - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o smtpd_reject_unlisted_recipient=no # -o smtpd_client_restrictions=$mua_client_restrictions # -o smtpd_helo_restrictions=$mua_helo_restrictions # -o smtpd_sender_restrictions=$mua_sender_restrictions # -o smtpd_recipient_restrictions= -o smtpd_relay_restrictions=permit_sasl_authenticated,reject -o milter_macro_daemon_name=ORIGINATING
6. Open postfix's main.cf file
[abernal@sandbox ~]$ sudo vim /etc/postfix/main.cf
7. Set the Fully Qualified Domain Name in postfix's main.cf file
myhostname = mail.apps.alejandrobernalcollazos.com
8. Set the $myorigin variable in postfix's main.cf file
myorigin = $mydomain
9. Start postfix service executing the next command
[abernal@sandbox ~]$ sudo postfix start
10. Test the configuration
[abernal@sandbox ~]$ mail -s "Hello World" someone@example.com Cc: Hi Peter How are you I am fine Good Bye <Ctrl+D>
11. Create the SSL Certificate folder (certs) within /etc/postfix
[abernal@sandbox postfix]$ sudo mkdir certs
12. Create the SSL Certificate (sample)
[abernal@sandbox postfix]$ sudo openssl req -new -x509 -days 3650 -nodes -out /etc/postfix/certs/cert.pem -keyout /etc/postfix/certs/key.pem Generating a 2048 bit RSA private key ...+++ .............................................+++ writing new private key to '/etc/postfix/certs/key.pem' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [XX]:AR State or Province Name (full name) []:Cordoba Locality Name (eg, city) [Default City]:Cordoba Organization Name (eg, company) [Default Company Ltd]:Asys Organizational Unit Name (eg, section) []:development Common Name (eg, your name or your server's hostname) []:apps.alejandrobernalcollazos.com Email Address []:alejandro@alejandrobernalcollazos.com
13. Modify postfix's main.cf file
[abernal@sandbox ~]$ sudo vim /etc/postfix/main.cf
14. Set these SSL variables
# TLS certificate parameter smtpd_tls_key_file = /etc/postfix/certs/key.pem smtpd_tls_cert_file = /etc/postfix/certs/cert.pem
15. Reload Postfix executing this command
[abernal@sandbox ~]$ sudo postfix reload
Reference document : http://www.shisaa.jp/postset/nikola-web.html