Most of the providers these days are blocking the default port 25 and users find it difficult to get around it. If you are looking at sending very less mails and do not want to go for paid stuffs, this is for you.

We will see how we can intergrate Postfix with Sendgrid which allows 40,000 emails for 30 days, then 100/day forever

First create an account at sendgrid, and get the API key, you would want this to be pasted in postfix configuration file.

Make sure to verify your domain at sendgrid ( )

Also verify a sender address from the domain you would be using for mailing ( )

Once that is done, lets move to the postfix configuration :

Open /etc/postfix/ and type in these values :

smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_security_level = encrypt
header_size_limit = 4096000
relayhost = []:587

As mentioned in the config file, we will need to create /etc/postfix/sasl_passwd file where we will store the API key.

It would be in the format : ( username by default is apikey )

[]:587 yourSendGridUsername:yourSendGridPassword
# chmod 600 /etc/postfix/sasl_passwd
# postmap /etc/postfix/sasl_passwd
# systemctl restart postfix

Lets test if this is working by using the mail command

If not present, install it

apt-get install mailutils
echo "the body of the mail" | mail -r -s "my subject"

The mail should be the email address you have verified in sendgrid.