Postfix

About Postfix

Postfix is Ubuntu’s default Mail Transfer Agent that aims to be easy and fast to administer and secure. Postfix is also compatible with the Mail Transfer Agent sendmail, this section goes over how to install and configure Postfix and how to set it up as an SMTP server using a secure connection.

Basic Configuration

Run the following command to configure Postfix:

sudo dpkg-reconfigure postfix

This will bring up the user interface, select the following values:

1. Internet site
2. Mail.example.com (replace this with the domain you’ll accept email from)
3. Appropriate username
4. Mail.example.com, localhost.localdomain, localhost
5. No
6. 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 (network and class range of your mail server)
7. 0
8. +
9. All

After doing this it would be good to decide the mailbox format that you want to use. Postfix will use mbox as their default mailbox format. You can use the command postconf to configure all Postfix parameters. 

SMTP Authentication

SMTP Authentication uses an authentication mechanism (SASL) to allow a client to identify itself. To encrypt the authentication process it is recommended you use Transport Layer Security (TLS). Once authenticated the SMTP server will allow the client to relay mail.