apt install mailutils<\/code><\/pre>\n\n\n\nDuring installation, you will be prompted to provide some information required to configure Postfix. The first prompts asks you to choose the type of configuration that best suits your environment. Select Internet Site<\/code> to enable Postfix to sent and received mails and press Enter to proceed.<\/p>\n\n\n\n![\"Configure](\"http:\/\/kifarunix.com\/wp-content\/uploads\/2019\/01\/internet-site.png\" "\\"\\"")
<\/a><\/figure><\/div>\n\n\nSet the mail name. Mail name specifies the domain part that is used in a mail ID, e.g example.com<\/code> for an email ID, userid@example.com<\/code>.<\/p>\n\n\n\n![\"\"](\"http:\/\/kifarunix.com\/wp-content\/uploads\/2019\/01\/post-fix-mail-name.png\" "\\"\\"")
<\/a><\/figure><\/div>\n\n\nPress Enter to finalize the installation.<\/p>\n\n\n\n
Note that you can always reconfigure Postfix by running the command below;<\/p>\n\n\n\n
dpkg-reconfigure postfix<\/code><\/pre>\n\n\n\nConfiguring Postfix to Use Gmail SMTP<\/h3>\n\n\n\n
Now that Postfix is installed, proceed to configure it to use Gmail as a mail relay.<\/p>\n\n\n\n
Open the Postfix configuration file, \/etc\/postfix\/main.cf<\/code> and configure is as follows;<\/p>\n\n\n\nvim \/etc\/postfix\/main.cf<\/code><\/pre>\n\n\n\nSet the Postfix relay server<\/h4>\n\n\n\n
Find the line, relayhost =<\/code> and setting its value to Gmail SMTPS such that it looks like<\/p>\n\n\n\nrelayhost<\/span> =<\/span> [<\/span>smtp.gmail.com]<\/span>:587<\/code><\/pre>\n\n\n\nNext add the following lines to the end of the configuration file.<\/p>\n\n\n\n
Enable SMTP Authentication<\/h4>\n\n\n\n
To enable SMTP server authentication, you need to;<\/p>\n\n\n\n
- Enable Cyrus-SASL support for authentication by setting the value of
smtp_sasl_auth_enable<\/code> to yes<\/code>.\nsmtp_sasl_auth_enable = yes<\/code><\/pre>\n<\/li>
- Configure Postfix to use the file with the SASL credentials. This can be done by defining the path to
sasl_passwd<\/code> as follows;\nsmtp_sasl_password_maps = hash:\/etc\/postfix\/sasl_passwd<\/code><\/pre>\n<\/li>
- Set the SASL security options to disable options that allows anonymous authentication.\n
smtp_sasl_security_options = noanonymous<\/code><\/pre>\n<\/li><\/ul>\n\n\n\nEnable STRTTLS Encryption<\/h4>\n\n\n\n
Enforce STARTTLS encryption for outgoing SMTP with Postfix by adding the following line. When a non-empty value is specified, this overrides the obsolete parameters smtp_use_tls<\/code>, smtp_enforce_tls<\/code>, and smtp_tls_enforce_peername<\/code>.<\/p>\n\n\n\nsmtp_tls_security_level<\/span> =<\/span> encrypt<\/code><\/pre>\n\n\n\nDefine the path to CA certificates. The public root certificates are usually found under \/etc\/ssl\/certs\/ca-certificates.crt<\/code> on Debian\/Ubuntu systems.<\/p>\n\n\n\nsmtp_tls_CAfile<\/span> =<\/span> \/etc\/ssl\/certs\/ca-certificates.crt<\/code><\/pre>\n\n\n\nThese lines should look like this;<\/p>\n\n\n\n
\n...\nrelayhost = [smtp.gmail.com]:587\n<\/strong>...\nsmtp_sasl_auth_enable = yes\nsmtp_sasl_password_maps = hash:\/etc\/postfix\/sasl_passwd\nsmtp_sasl_security_options = noanonymous\nsmtp_tls_security_level = encrypt\nsmtp_tls_CAfile = \/etc\/ssl\/certs\/ca-certificates.crt<\/strong>\n<\/code><\/pre>\n\n\n\nAdd Credentials to sasl_passwd<\/h4>\n\n\n\n
Since Postfix is acting a as mail client, it has to know when to provide a username and password. Therefore, create the sasl_passwd file define above, \/etc\/postfix\/sasl_passwd<\/code> and set the credentials of the mail relay server as shown below;<\/p>\n\n\n\nvim \/etc\/postfix\/sasl_passwd<\/code><\/pre>\n\n\n\n[smtp.gmail.com]:587 userid@gmail.com:password<\/code><\/pre>\n\n\n\nReplace your email ID appropriately.<\/p>\n\n\n\n
Secure sasl_passwd<\/h4>\n\n\n\n
The credentials are set in plaintext. Hence to make it abit secured, change ownership and permission to root<\/code><\/tt> and read-write<\/code> only respectively.<\/p>\n\n\n\nchown root:root \/etc\/postfix\/sasl_passwd\nchmod 600 \/etc\/postfix\/sasl_passwd<\/code><\/pre>\n\n\n\nCreate sasl_passwd DB file<\/h4>\n\n\n\n
Postfix requires that the sasl_passwd<\/code> file to be a database such that it can be read faster. Use postmap<\/code> command to convert the file into a database, sasl_passwd.db<\/code><\/span>.<\/p>\n\n\n\npostmap \/etc\/postfix\/sasl_passwd<\/code><\/pre>\n\n\n\nThis will assign the same ownership and permissions to the database file as set for the sasl_passwd file above.<\/p>\n\n\n\n
ls -l \/etc\/postfix\/sasl_passwd*\n-rw------- 1 root root 51 Jan 6 21:57 \/etc\/postfix\/sasl_passwd\n-rw------- 1 root root 12288 Jan 6 22:04 \/etc\/postfix\/sasl_passwd.db<\/code><\/pre>\n\n\n\nRestart Postfix<\/p>\n\n\n\n
sudo systemctl restart postfix<\/code><\/pre>\n\n\n\nSend a Test Mail<\/h3>\n\n\n\n
To verify that all is well, send the test mail as shown below;<\/p>\n\n\n\n
echo \"Test Postfix Gmail Relay\" | mail -s \"Postfix Gmail Relay\" userid@gmail.com<\/code><\/pre>\n\n\n\nYou can tail the logs to check what is happening. If you encounter such an error ...SASL authentication failed; server smtp.gmail.com...<\/code>, you need to allow less secure apps to access your gmail account<\/a>. Otherwise, you should be able to receive the test mail.<\/p>\n\n\n\nNOTE that the use of less secure app access has been deprecated. See how you can use App password as an alternative in the guide below;<\/p>\n\n\n\n
Configure Postfix to Use Gmail App Passwords<\/a><\/p>\n\n\n\n