Embed images for use in email message using PHP?

Question

I know how to embed an image into an email as an attachment, but that's not really what I want to do. What I want to do is embed an image into the message and use that within the body of the email message itself. Is it possible to do this or possibly reference an attached file somehow to be used in the message?

Should I even worry about this? Is it more beneficial to just load them via a link to the image on my network? I was thinking that this would take some load off my server so it didn't have to be downloaded directly from my site in every email message that got opened, thus reducing bandwidth a little.

Note: I'm not looking for any email frameworks or libraries etc, just for a simple way to accomplish this task.

Answer 1

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I think the only way to do this is to reference a image by url like this:

<img src="http://www.youwebsite.com/yourimage.jpg" alt="This is a description" />

Answer 2

People will chime in to tell you to use SwiftMailer or some other library. But it's not that hard. It's really finicky, but not hard. Below is a function I use. I've anonymized it a bit, and hopefully didn't break anything. In the html message (which I get from another function), link to your attached image this way:

$output .= '<p><img src="cid:' . $linkID . '" alt="graph" /></p>';

Where $linkID is the same value used in the function below.

public function sendEmail($emailAddress)
{
    $random_hash = md5(date('r', time()));

    $htmlString = $this->getHTML($random_hash);

    $message = "--mixed-$random_hash\n";
    $message .= 'Content-Type: multipart/alternative; boundary="alt-' . $random_hash . '"' . "\n\n";
    $message .= 'MIME-Version: 1.0' . "\n";
    $message .= '--alt-' . $random_hash . "\n";
    $message .= 'Content-Type: text/plain; charset="iso-8859-1"' . "\n";
    $message .= 'Content-Transfer-Encoding: 7bit' . "\n\n";

    // text message
    $message .= strip_tags($htmlString) . "\n\n";

    $message .= '--alt-' . $random_hash . "\n";
    $message .= 'Content-Type: text/html; charset="iso-8859-1"' . "\n";
    // $message .= 'MIME-Version: 1.0' . "\n";
    $message .= 'Content-Transfer-Encoding: 7bit' . "\n\n";

    // html message
    $message .= $htmlString . "\n\n";

    $message .= '--alt-' . $random_hash . '--' . "\n";

    // graph image
    if($this->selectedGraph != 0)
    {
        $graphString = $this->getGraph();
        $graphString = chunk_split(base64_encode($graphString));

        $linkID = 'graph-' . $random_hash . '-image';

        $message .= '--mixed-' . $random_hash . "\n";
        $message .= 'MIME-Version: 1.0' . "\n";
        $message .= 'Content-Transfer-Encoding: base64' . "\n";
        $message .= 'Content-ID: ' . $linkID . "\n";
        $message .= 'Content-Type: image/gif; name="graph.gif"' . "\n";
        $message .= 'Content-Disposition: attachment' . "\n\n";

        $message .= $graphString;
        $message .= '--mixed-' . $random_hash . '--' . "\n";

    }
    else
    {
        $message .= '--mixed-' . $random_hash . '--' . "\n";
    }


    $headers = 'From: ' . $this->from. "\r\nReply-To: " . $this->replyto;
    $headers .= "\r\nContent-Type: multipart/related; boundary=\"mixed-" . $random_hash . "\"\r\nMIME-Version: 1.0";

    $flags = '-f ' . BOUNCED_EMAIL_ADDRESS;

    return mail($emailAddress, $this->subject, $message, $headers, $flags);

}

Whether or not it's worthwhile to do is another question. If you attach the image, you're using bandwidth to send the message out. Maybe it's better for you to use the bandwidth all at once rather than spread out? Maybe not.

I didn't use attached images until I had to send out a different image to each recipient. I wasn't about to store and manage all of those images on our server (and try to uniquely name them).

Answer 3

Content-Type: multipart/related;
  type="text/html";
  boundary="Boundary1"


--Boundary1
Content-Type: multipart/alternative;
boundary="Boundary2"

--Boundary2
Content-Type: text/html; charset = "utf-8"
Content-Transfer-Encoding: 8bit

<img src="cid:content_id_from_attachment">

--Boundary2--

--Boundary1
Content-Type: image/jpeg; name="somefilename.jpg"
Content-Transfer-Encoding: base64
Content-ID: <content_id_from_attachment>
Content-Disposition: inline; filename="somefilename.jpg"

//binary data

--Boundary1--

Boundary, charset, Content-Transfer-Encoding of course all choosable. The PHPMailer package can do this automatically for you: http://www.ustrem.org/en/article-send-mail-using-phpmailer-en/

See also including images at: http://mailformat.dan.info/body/html.html