Pipe Email To PHP And Parse Content

Did you ever think about how an email group works behind the screen? You send an email to an email address(a unique email address dedicated to an email group). It is being saved and shown on the email group’s web page and also sent out to all email addresses of members of this group. So, you will need to process the email contents to save them to DB, publish them on the webpage and send emails to others.

How PHP Email Piping Works:

In this tutorial, I will try to demonstrate the main part of a similar application as follows:

• How we can send an email’s content/information to a PHP handler on a Linux server
• How can we parse the email contents into necessary parts like sender/subject/content?

So, in order to achieve these above goals, in this pipe email to the PHP tutorial, we are going to implement the following two requirements:

1. Forward an email to a PHP script.
2. Retrieve the necessary contents by PHP.

Forward an email to a PHP script:

This part is pretty straightforward and doesn’t involve any coding. However, your hosting may or may not support this feature, so make sure first and contact support if it doesn’t find out whether there is any way to do so(maybe by upgrading the hosting package, etc.).

Firstly, log in to your hosting “cpanel”(Screenshots here are from host-gator).

Then, find the main section, where you should see an option named ‘Forwarder’ or similar. Enter this section, and then click on the ‘Add forwarder’ button.

This section provides you with the option to take several actions whenever an email reaches the address it handles. We will be using the “Pipe to a program” option, which is the only option to forward it to a PHP script (Just to mention, you can use other languages too, not necessarily PHP, as long as that language is supported in your server). On this option, you will have to enter the path to the PHP handler file. Here, carefully remember three things:

• If you enter the PHP script’s URL here, it won’t work. You have to provide the local path location (like “public_html/handlers/email_handler.php” or something similar).
• You should specify the PHP compiler path at the beginning (e.g., “/usr/bin/php”).
• You must ensure that the handler file has ‘execute’ permission. Otherwise, this command will not be executed.

So basically, your command string here will be like a terminal command. One example is as follows:

/usr/local/bin/php -q /home/yourdomain/public_html/handlers/mail_to_group.php

Retrieve necessary contents from email by PHP:

First, we need to get the contents. To do so, on your handler PHP file, please add the following directive at the very top of the page(it may vary for you; refer to the previous section; need the path of the PHP compiler correctly):

#!/usr/local/bin/php -qCode language: JavaScript (javascript)

This will not be under the PHP tag; it will be outside. The PHP tag should start after it.

Now, the following code snippet will retrieve the entire content received:

$fd = fopen("php://stdin", "r");
$email_content = "";
while (!feof($fd)) {
$email_content .= fread($fd, 1024);
}
fclose($fd);Code language: PHP (php)

After executing the code snippet, we will receive the full content in the “$email_content” variable.

Ok, so as we are now ready to get the contents from email, we can move ahead and parse it as you will receive the contents in some wired manner, not every piece differently. Wanna see what it looks like? Here is an example 🙂 :

Return-path: <senderemail@domain.com>
Received: from mail-wy0-f179.google.com ([74.125.82.179]:53218)
       by gator526.hostgator.com with esmtps (TLSv1:RC4-SHA:128)
       (Exim 4.69)
       (envelope-from <senderemail@domain.com>)
       id 1Qetnx-00061q-E5
       for recieveremail@domain.org; Thu, 07 Jul 2011 14:00:05 -0500
Received: by wyh21 with SMTP id 21so939158wyh.38
       for <recieveremail@domain.org>; Thu, 07 Jul 2011 12:00:06 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
       d=gmail.com; s=gamma;
       h=mime-version:date:message-id:subject:from:to:content-type;
       bh=aVvn1hmmUfdWAswRt69lpHB1V8XJtvcueoBNWIIKkV8=;
       b=o1jHeVKd8ollKyXuUlTpCG+DIS8eY1qoueyTaSYTyEqIFgiynuoX1NXTKzT9+l8SU/
        LCqUoNYxofOtjNhkhJ7wS5mOQvoZVEnMyONTwRrx024PJE4/Do5VLltwNjPRzqMrFPux
        otJCyqSddue/SGlTPxbBXiFsD7Gzl3TcTTdz8=
MIME-Version: 1.0
Received: by 10.216.237.131 with SMTP id y3mr7444080weq.87.1310065206713; Thu,
 07 Jul 2011 12:00:06 -0700 (PDT)
Received: by 10.216.237.170 with HTTP; Thu, 7 Jul 2011 12:00:06 -0700 (PDT)
Date: Fri, 8 Jul 2011 01:00:06 +0600
Message-ID: <CAAxg_qAWbasvps0Q-2FAjXZ73zWzMErztqp5U_aUYUTCsxP6LQ@mail.domain.com>
Subject: [Demo - Test Group] Test topic 6
From: "Sender Full Name" <senderemail@domain.com>
To: Email Group <recieveremail@domain.org>
Content-Type: multipart/alternative; boundary=0015175cfc46475cbc04a77f53d6

--0015175cfc46475cbc04a77f53d6
Content-Type: text/plain; charset=ISO-8859-1

another new test topic.
--
Regards

Rana

--0015175cfc46475cbc04a77f53d6
Content-Type: text/html; charset=ISO-8859-1

<br clear="all">another new test topic.<br>-- <br>Regards<br><br>Rana<br>

--0015175cfc46475cbc04a77f53d6--Code language: HTML, XML (xml)

So, how is it? Do you like it? I hope not; I didn’t like it at all :D. So, what we need now is to parse it. Well, though you can do it yourself by spending some time, here is some ready-made code you can reuse all the time. Here we go:

//split the string into array of strings, each of the string represents a single line, received
$lines = explode("\n", $email_content);

// initialize variable which will assigned later on
$from = "";
$subject = "";
$headers = "";
$message = "";
$is_header= true;

//loop through each line
for ($i=0; $i < count($lines); $i++) {
if ($is_header) {
// hear information. instead of main message body, all other information are here.
$headers .= $lines[$i]."\n";

// Split out the subject portion
if (preg_match("/^Subject: (.*)/", $lines[$i], $matches)) {
$subject = $matches[1];
}
//Split out the sender information portion
if (preg_match("/^From: (.*)/", $lines[$i], $matches)) {
$from = $matches[1];
}
} else {
// content/main message body information
$message .= $lines[$i]."\n";
}
if (trim($lines[$i])=="") {
// empty line, header section has ended
$is_header = false;
}
}Code language: PHP (php)

So, after this, in the end, you should get from, to, subject, and message information in their corresponding variables.

Final Words:

Remember, your message body structure will differ slightly from one email client to another. So, you must take care of the client you are using. If you want to support most clients (Yahoo/Google/Hotmail), you may have to apply several parsing rules to the message to get the text and/or HTML version.

To debug how it’s working, you can’t do it on the browser as the contents will go from email, so you should use logging on an external text file and write a log about each step and error to get full details.

Hopefully, this pipe email to PHP tutorial will help you understand how the process works. Those are just the fundamental yet most essential parts of the way to build an email group. Let me know if you have any questions. Happy coding 🙂