Fix the SPF neutral message when you send email through Amazon's EC2 instance

If you got the following SPF neutral message when you send email through Amazon's EC2 instance:

Received-SPF: neutral (google.com: 51.11.171.201 is neither permitted nor denied by best guess record for domain of root@ip-171-31-11-41.us-west-2.compute.internal) client-ip=51.11.171.201;

Solution:

Set host name:

# hostnamectl set-hostname host1.example.com

# hostnamectl status

# cat /etc/hostname

Append the following string at the bottom of the file to ensure that the hostname is preserved between restarts/reboots:

# vim /etc/cloud/cloud.cfg

preserve_hostname: true

More info: https://aws.amazon.com/premiumsupport/knowledge-center/linux-static-hostname-rhel7-centos7/

Contact Amazon to add a reverse DNS record:

You can contact Amazon to request to remove email sending limitations:

https://aws.amazon.com/forms/ec2-email-limit-rdns-request

Input your Elastic IP Address 1: 51.11.171.201

Input Reverse DNS Record for EIP 1: host1.example.com (this is the Amazon EC2 instance you will be using to send out emails).

Create a sample script:

# vim test_send.php

<?php
$from    = 'info@example.com';
$to      = 'someone@abc.com';

$subject = 'test subject 6';
$message = 'test subject 6';

$headers = 'From: ' . $from . "\r\n" .
    'Reply-To: ' . $from . "\r\n" .
    'X-Mailer: PHP/' . phpversion();

mail($to, $subject, $message, $headers);
?>

Show email original:

Received-SPF: pass (google.com: best guess record for domain of user1@host1.example.com designates 51.11.171.201 as permitted sender) client-ip=51.11.171.201;

Reference:

http://aws.amazon.com/ec2/faqs/#Are_there_any_limitations_in_sending_email_from_EC2_instances
https://aws.amazon.com/premiumsupport/knowledge-center/route-53-reverse-dns/