To attach a file to an email message, you have to create a multipart MIME message.

• Pass these headers as the fourth parameter to mail():

  MIME-Version: 1.0 Content-Type: multipart/mixed;
  boundary="php-12345"

  Note the boundary on the end of the Content-Type. The boundary is an arbitrary US-ASCII string that tells MUAs when the end of a MIME block has been reached. You can set it to be whatever you want, provided you set it to something that isn't going to appear in your email message.

• The first part of your message string should be a plain text message like this:

  If you are reading this, it means that your email
  client does not support MIME. Please upgrade your email
  client to one that supports MIME. —php-12345

  Note the boundary marker after the message. This tells MIME that you've reached the end of this particular part of the email message. You can now add more parts to your email message.

• The second part of your "message" string should be the message itself. You need to add Content-Type and Content-Transfer-Encoding headers to the message, followed by the message itself.

  Content-Type: text/plain; charset="iso-8859-1"
  Content-Transfer-Encoding: 7bit
  Hello, this is my plain text message. If you can see
  this, then hopefully my MIME email is working fine.
  —php-12345

  Note the boundary marker after the message. You have to put the boundary marker at the end of each part of the message.

• Next come the attachments. Each attachment gets added to the "message" string as well. You need to add Content-Type and Content-Transfer-Encoding headers, and then the attachment.

  If the attachment isn't plain text, you should encode it using base64 encoding:

  Content-Type: image/jpeg
  Content-Transfer-Encoding: base64
  <message goes here>
  —php-12345

<?php

// who is the email going to?
// change this to be *your* email address ;-)

$to = "stuart";

// what is the message?

$message = "This is my third email sent from "
         . "<a

href="http://www.php.net">PHP</a>.\r\n"
         . "This email has an attached image\r\n";

// don't forget our blank line
$blank_line = "\r\n";

// define our boundary
$boundary_text = "php-12345";
$boundary = "—" . $boundary_text . "\r\n";
$last_boundary = "—" . $boundary_text . "—\r\n";

// add the MIME headers

$more_headers = "MIME-Version: 1.0\r\n"
              . "Content-Type: multipart/mixed;

boundary=""
              . $boundary_text
              . ""\r\n";

// create the first part of the message
$mime_message = "If you are reading this, it means

that your e-mail client\r\n"
              . "does not support MIME.  Please

upgrade your e-mail client\r\n"
              . "to one that does support MIME.\r\n"
              . $boundary;

// add the second part of the message
$mime_message .= "Content-Type: text/html;

charset="iso-8859-1"\r\n"
              .  "Content-Transfer-Encoding:

7bit\r\n"
              .  $blank_line
              .  $message
              .  $boundary; 

// now add the attachment
$mime_message .= "Content-Type: image/gif;

name="php.gif"\r\n"
              .  "Content-Transfer-Encoding:

base64\r\n"
              .  "Content-disposition: attachment;

file="php.gif"\r\n"
              .  $blank_line
              .  chunk_split(base64_encode

(file_get_contents("php.gif")))
              .  "\r\n"
              .  $last_boundary;

// send the email

$result = mail (
        $to,
        "My first HTML e-mail with an attachment",
        $mime_message,
        $more_headers
);

?>

You can add as many attachments as you want, but remember—they can make the email quite large to download, and many users are still using dial-up rather than broadband!

The last boundary marker in the email message must end with —. For example, if our boundary marker is

—php-12345

the last marker in the email message would be

—php-12345—

instead.