多部分电子邮件在eM Client中显示不正确

Question

I have a multi-part email script, that takes a POSTed email address and sends a simple email to them in HTML and/or Plain Text. It displays correctly in Gmail and Outlook, but not eM (and doesn't even get through to a Communigate server). The code:

<?php
$email_address = addslashes($_POST['email_address']);

if (!filter_var($email_address, FILTER_VALIDATE_EMAIL)) {
    header("Location: ./?error=invalid-email");
    exit();
}

$subject_line = "This is a test multi-part email";

$boundary = uniqid();

$headers  = "MIME-Version:1.0
";
$headers .= "From: Maggie Multipart <[e-mail]>
";
$headers .= "To: " . $email_address . "
";
$headers .= "Content-Type: multipart/alternative;boundary=" . $boundary . "
";

$message  = "This is a MIME encoded message.";
$message .= "

--" . $boundary . "
";

$message .= "Content-Type: text/plain;charset=utf-8

";
$message .= "Hello,
This is a test email, the text/plain version.

Regards
Maggie Multipart";
$message .= "

--" . $boundary . "
";

$message .= "Content-Type: text/html;charset=utf-8

";
$message .= "<p>Hello,<br>This is a test email, the text/html version.</p><p>Regards<br><strong>Maggie Multipart</strong></p>";
$message .= "

--" . $boundary . "--";

mail("", $subject_line, $message, $headers);

header("Location: ./?success=email-sent");
exit();

// var_dump($_POST);
?>

The message is received in eM as follows:

Content-Type: text/plain;charset=utf-8

Hello,

This is a test email, the text/plain version.

Regards

Maggie Multipart

However, eM is set up to receive HTML emails (and does so frequently). Can someone please help me fix this problem? Am I missing any headers?

Answer 1

My general advice for creating emails: Don't do it yourself (with some string concat functions/operators anyway). My weapon of choice is swiftmailer but there are other feasible libraries on the web, too.

<?php
require_once('autoload.php'); // swiftmailer was installed via Composer

$message = Swift_Message::newInstance('This is a test multi-part email')
    ->setBody(
        "Hello,
This is a test email, the text/plain version.

Regards
Maggie Multipart",
        'text/plain',
        'utf-8'
    )
    ->addPart(
        "<p>Hello,<br>This is a test email, the text/html version.</p><p>Regards<br><strong>Maggie Multipart</strong></p>",
        'text/html',
        'utf-8'
    )
    ->setFrom(array('...@...' => '...'))
    ->setTo(array('...@...' => '...'));

$transport = Swift_SmtpTransport::newInstance('MSERV', 25, 'tls')
  ->setUsername('...')
  ->setPassword('...');

$mailer = Swift_Mailer::newInstance($transport);
$result = $mailer->send($message);