Swiftmailer is a very good library for sending email from PHP. It has nice object oritented interfaces. However, in recent days I’ve spent a lot of time finding the reason why the content get messed up in Swiftmailer when

• The email has both html and alternate text content
• Embed image in html content

Specification wise, mime structure for HTML with embedded images and plain text fallback is :

multipart/alternative
  text/plain
  multipart/related
    text/html
    image/png
    image/png
    image/jpeg

Swiftmailer has a bug and fails to generate correct mime type entries. The issue is reported here . Thankfully there is a workaround for that.

My previous code was:

$message = Swift_Message::newInstance();

$message->setSubject('Your subject')
        ->setFrom(array('[email protected]' => 'Saroj Roy'))
        ->setTo(array('saroj@saroj-HP-ProBook-4530s'))
        ->setBody('This is a plain text Message','text/plain')       
        ->addPart('Here is the <b>HTML message</b> with image : <img src="' .
                  $message->embed(Swift_Image::fromPath('image.png')).
                  '" alt="Image Missing" />', 'text/html');

$mailer = Swift_Mailer::newInstance(Swift_MailTransport::newInstance());

$result = $mailer->send($message);

I had to change the setBody() to addPart(). This change generates correct mime-type entries in message. However, this is still not 100% full-proof. Problem still occurs in MS Office 2003 and Thunderbird email client when content is viewed as text. These clients convert the html content to text by striping the html-tags out instead of showing the plain-text content. I suppose there are some bugs in these email clients. Please let me know it I were wrong with my assumptions.

By the way, Gmail and console based email client Mutt shows the content correctly.