Use Gmail SMTP on Ubuntu

Summary:
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We can use Gmail account as a free SMTP server on your Ubuntu system. The configuration as following steps

Step 1:
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Install postfix and associated packages

$ sudo apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules


Step 2:
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Open your postfix config file:

vim /etc/postfix/main.cf

add the following command

relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_use_tls = yes

Step 3:
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Configure gmail username and password

open sasl_passwd file or create

$ vim /etc/postfix/sasl_passwd

Add the  username and password

[smtp.gmail.com]:587    USERNAME@gmail.com:PASSWORD


Step 4:
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Apply permission for the created file

sudo chmod 400 /etc/postfix/sasl_passwd
sudo postmap /etc/postfix/sasl_passwd


Step 5:
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Create certificate file for authenticate

$ cat /etc/ssl/certs/Server_CA.pem | sudo tee -a /etc/postfix/cacert.pem

Step 6:
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Reload the postfix server

$ sudo /etc/init.d/postfix reload

Step 7:
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Check mail weather its sending or not

$ echo "Test mail from postfix" | mail -s "Test Postfix" you@example.com