How to Configure Postfix with Gmail on Ubuntu

In this article we are going to cover how to configure Postfix with Gmail on Ubuntu/How to Send alerts to mail inbox from Linux Server

Switch to root user using below command:

sudo su

Step#1:Install Postfix on Ubuntu

Install Postfix using below command:

apt-get install libsasl2-modules postfix

There will be prompts asking General type of mail configuration. Select Internet Site:

Enter the fully qualified name of your domain.

Step#2: Update Postfix main.cf file

After installation of postfix, ensure that the myhostname parameter is configured As shown below

root@ip-172-31-0-205:/home/ubuntu# cat /etc/postfix/main.cf | grep ^myhostname

Output:

myhostname = ip-172-31-0-205.ap-south-1.compute.internal

Step #3:Generate Google App Password for Postfix

We need to generate an App password

Log in to your email, then click the following link: Manage your account access and security settings.

Scroll down to “Signing into Google” and click 2-Step Verification. You may be asked for your password and a verification code before continuing. Ensure that 2-Step Verification is enabled.

Click the following link to Generate an App password for Postfix:

Click Select app and choose Other (custom name) from the dropdown. Enter “Postfix” and click Generate.

After generate password you will see like this save your password in secure place

Step #4:Add Gmail Username and App Password to Postfix configuration

You need to add your username and password in this file sasl_passwd to this directory /etc/postfix/sasl/

Create /etc/postfix/sasl/sasl_passwd file and add your gmail ID and password we have just created using below command

root@ip-172-31-0-205:/etc/postfix/sasl# sudo nano sasl_passwd

And add your gmail ID and password as shown in below

[smtp.gmail.com]:587 [email protected]:logwrbyaqcmwslqp

If you wants to check your gmail Id and password then run the below command:

root@ip-172-31-0-205:/etc/postfix/sasl# cat /etc/postfix/sasl/sasl_passwd
[smtp.gmail.com]:[email protected]:logwrbyaqcmwslqp
root@ip-172-31-0-205:/etc/postfix/sasl#

create the hash file for Postfix using the postmap command

postmap /etc/postfix/sasl/sasl_passwd

After execute postmap command you should have a new file named sasl_passwd.db in the /etc/postfix/.

root@ip-172-31-0-205:/etc/postfix/sasl# ls
sasl_passwd  sasl_passwd.db
root@ip-172-31-0-205:/etc/postfix/sasl#

Step #5:Secure Your Postfix Hash Database and Email Password Files

chown root:root /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db

chmod 0600 /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db

Step #6:Configure Relay Host postfix with gmail

Modify the main.cf file using below command:

sudo nano /etc/postfix/main.cf

Set the relayhost

relayhost = [smtp.gmail.com]:587

If yu want to check your relayhost set or not then run the below command and you will get output like this:

root@ip-172-31-0-205:/etc/postfix# cat /etc/postfix/main.cf | grep -i ^relayhost
relayhost = [smtp.gmail.com]:587
root@ip-172-31-0-205:/etc/postfix#

Step #7:Add Custom Configuration 

Open main.cf file and this below line end on the file

sudo nano /etc/postfix/main.cf

# Enable SASL authentication
smtp_sasl_auth_enable = yes
# Disallow methods that allow anonymous authentication
smtp_sasl_security_options = noanonymous
# Location of sasl_passwd
smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd
# Enable STARTTLS encryption
smtp_tls_security_level = encrypt
# Location of CA certificates
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

You need to restart your postfix

systemctl restart postfix

Step #9:Send Email using sendmail

Lets test whether our SMTP server

sendmail [email protected]
From: [email protected]
Subject: Test mail
Testing Email
.

In this article we have covered how to configure Postfix with Gmail on Ubuntu.

Related Articles:

How to Configure Sendmail to Relay Emails using Gmail SMTP on Ubuntu 18.04

Reference:

Postfix Official page