php mail and SMTP while using cloudflare

Question

I am using cloudflare on my website and I want to keep my server's IP (the ORIGIN IP) private, to avoid DDoS attacks being sent directly to my server's IP. My server uses Apache, PHP, MySQL.

When using php mail to send emails (even if I use phpmailer library to send the emails through external SMTP) the IP of my server is added to the mail headers. It happens with Google SMTP, Mailgun and others, because probably it is in their policy to write in the header the IP from which the mail came.

At the moment, the only solution that I have in mind and requires a lot of effort, which is to create my own REST API and send emails through another server, something like this:

ORIGIN SERVER IP sends email data in text format via my REST API to MY MAIL SERVER IP and then MY MAIL SERVER IP uses php mail function with phpmailer to send the email via SMTP to the user. This way, the IP of MY MAIL SERVER will appear in the email headers and not the IP of the ORIGIN SERVER.

Is there a much more elegant way to do this? Is there a mail service that offers a rest API and if I use their API, they won't display my server's IP in the email headers? Or maybe there is an already developed REST API / library for sending emails remotely as I requested, so I won't have to develop and test my own from scratch?

Answer 1

You should send emails through mailgun (or sendgrid, or jetmail, or SES, or ...) through their API and not the SMTP protocol and your IP won't be disclosed.

For instance for Mailgun SDK: https://github.com/mailgun/mailgun-php

$mg = Mailgun::create('key-example');

# Now, compose and send your message.
# $mg->messages()->send($domain, $params);
$mg->messages()->send('example.com', [
  'from'    => '[email protected]',
  'to'      => '[email protected]',
  'subject' => 'The PHP SDK is awesome!',
  'text'    => 'It is so simple to send a message.'
]);

But there are SDK for most providers:

• Sendgrid php sdk
• Mailjet php sdk
• AWS SES PHP SD

Moreover, I would recommend using SwiftMailer which is powerful library to handle email. One of the cool thing is that it abstract the transport and you would be able to switch from SMTP or any provider API using packages.