问题描述
总结
由于 WP Core 中存在错误，因此使用 wp_mail()发送 multipart 电子邮件 (html / text)(以减少垃圾邮件文件夹中的电子邮件结果的可能性)，会导致您的域被 Hotmail(和其他 Microsoft 电子邮件) 阻止。
这是一个复杂的问题，我将致力于细细分解，以试图帮助某人找到可能最终在核心中实现的可行解决方案。
这将是一个有益的阅读。让我们开始…
错误
最常见的建议是避免将通讯电子邮件最终发送到垃圾邮件文件夹中，是发送多部分消息。
Multi-part(mime) 是指在单个电子邮件中发送电子邮件的 HTML 和 TEXT 部分。当客户端收到多部分消息时，它接受 HTML 版本，如果它可以呈现 HTML，否则它会显示纯文本版本。
这被证明是有效的。发送到 Gmail 时，我们的所有电子邮件都将登陆垃圾邮件文件夹，直到我们将邮件更改为 multipart，当他们进入主收件箱时。好东西。
现在，当通过 wp_mail() 发送多部分消息时，它会输出内容类型 (multipart / *) 两次，一次使用边界 (如果自定义)，一次不会。这种行为导致电子邮件显示为原始邮件，而不是在某些电子邮件中展示，包括所有 Microsoft(Hotmail，Outlook 等)
微软将此邮件标记为垃圾邮件，并且通过的几条邮件将被收件人手动标记。不幸的是，Microsoft 电子邮件地址被广泛使用。我们 40％的用户使用它。
这是微软通过我们最近通过电子邮件交换确认的。
邮件的标记将导致域被完全阻止。这意味着邮件不会发送到垃圾邮件文件夹，甚至不会将邮件发送到收件人。
到目前为止，我们的主要域名已经被阻止了 3 次。
因为这是 WP 核心中的一个错误，所以发送多部分消息的每个域都被阻止。问题是大多数网站管理员不知道为什么。我在进行研究和查看其他用户在论坛上讨论这个问题时已经证实了这一点。它需要深入了解原始代码，并且很好地了解这些类型的电子邮件的工作原理，我们将要下一步…
我们把它分解成代码
创建一个 hotmail / outlook 帐户。然后，运行以下代码：
// Set $to to an hotmail.com or outlook.com email
$to = "YourEmail@hotmail.com";
$subject = 'wp_mail testing multipart';
$message = '------=_Part_18243133_1346573420.1408991447668
Content-Type: text/plain; charset=UTF-8
Hello world! This is plain text...
------=_Part_18243133_1346573420.1408991447668
Content-Type: text/html; charset=UTF-8
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<p>Hello World! This is HTML...</p>
</body>
</html>
------=_Part_18243133_1346573420.1408991447668--';
$headers = "MIME-Version: 1.0rn";
$headers .= "From: Foo <foo@bar.com>rn";
$headers .= 'Content-Type: multipart/alternative;boundary="----=_Part_18243133_1346573420.1408991447668"';
// send email
wp_mail( $to, $subject, $message, $headers );
如果要更改 default content type，请使用：
add_filter( 'wp_mail_content_type', 'set_content_type' );
function set_content_type( $content_type ) {
return 'multipart/alternative';
}
这将发送一个多部分消息。
因此，如果您查看消息的完整原始来源，您会注意到内容类型被添加了两次，一次没有边界：
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="====f230673f9d7c359a81ffebccb88e5d61=="
MIME-Version: 1.0
Content-Type: multipart/alternative; charset=
这是问题。
问题的根源在于 pluggable.php – 如果我们在这里看到某处：
// Set Content-Type and charset
// If we don't have a content-type from the input headers
if ( !isset( $content_type ) )
$content_type = 'text/plain';
/**
* Filter the wp_mail() content type.
*
* @since 2.3.0
*
* @param string $content_type Default wp_mail() content type.
*/
$content_type = apply_filters( 'wp_mail_content_type', $content_type );
$phpmailer->ContentType = $content_type;
// Set whether it's plaintext, depending on $content_type
if ( 'text/html' == $content_type )
$phpmailer->IsHTML( true );
// If we don't have a charset from the input headers
if ( !isset( $charset ) )
$charset = get_bloginfo( 'charset' );
// Set the content-type and charset
/**
* Filter the default wp_mail() charset.
*
* @since 2.3.0
*
* @param string $charset Default email charset.
*/
$phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );
// Set custom headers
if ( !empty( $headers ) ) {
foreach( (array) $headers as $name => $content ) {
$phpmailer->AddCustomHeader( sprintf( '%1$s: %2$s', $name, $content ) );
}
if ( false !== stripos( $content_type, 'multipart' ) && ! empty($boundary) )
$phpmailer->AddCustomHeader( sprintf( "Content-Type: %s;nt boundary="%s"", $content_type, $boundary ) );
}
if ( !empty( $attachments ) ) {
foreach ( $attachments as $attachment ) {
try {
$phpmailer->AddAttachment($attachment);
} catch ( phpmailerException $e ) {
continue;
}
}
}
潜在的解决方案
所以你想知道，为什么你没有在 trac 报告？我 already have 。令我惊奇的是，different ticket 是在 5 年前创建的，它概述了同样的问题。
我们来面对现在，已经过了半个十年。在互联网年代，这更像是 30. 这个问题已经被明确地放弃了，基本上永远不会被修改 (除非我们在这里解决) 。
我发现一个伟大的 thread here 提供了一个解决方案，但是当他的解决方案工作时，它会打破没有自定义 $headers 设置的电子邮件。
这就是我们每次崩溃的地方。多部分版本都能正常工作，并且正常未设置的 $headers 消息不会被修改，也不能修改。
我们提出的解决办法是：
if ( false !== stripos( $content_type, 'multipart' ) && ! empty($boundary) ) {
$phpmailer->ContentType = $content_type . "; boundary=" . $boundary;
}
else {
$content_type = apply_filters( 'wp_mail_content_type', $content_type );
$phpmailer->ContentType = $content_type;
// Set whether it's plaintext, depending on $content_type
if ( 'text/html' == $content_type )
$phpmailer->IsHTML( true );
// If we don't have a charset from the input headers
if ( !isset( $charset ) )
$charset = get_bloginfo( 'charset' );
}
// Set the content-type and charset
/**
* Filter the default wp_mail() charset.
*
* @since 2.3.0
*
* @param string $charset Default email charset.
*/
$phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );
// Set custom headers
if ( !empty( $headers ) ) {
foreach( (array) $headers as $name => $content ) {
$phpmailer->AddCustomHeader( sprintf( '%1$s: %2$s', $name, $content ) );
}
}
是的，我知道，编辑核心文件是禁忌的，请坐下来… 这是一个绝望的修复，并且尝试提供一个核心的修复。
我们修复的问题是，默认电子邮件，如新注册，注释，密码重置等将作为空白消息传递。所以我们有一个 working wp_mail() 脚本将发送多部分消息，但没有别的。
该怎么办
这里的目的是找到一种使用 core wp_mail() 函数 (而不是自定义 sendmail 函数) 发送普通 (纯文本) 和多部分消息的方法。
当您尝试解决这个问题时，您将遇到的主要问题是您花费在发送虚拟消息的时间，检查是否收到，并且基本上打开一盒阿司匹林并诅咒 Microsoft，因为您习惯了他们 IE 问题，而这里的 gremlin 不幸的是 WordPress 。
Update
@bonger 发布的解决方案允许 $message 是一个包含 content-type 键控的数组的数组。我已经确认它在所有情况下都有效。
我们将允许这个问题保持开放，直到获得充足的利益来提高对这个问题的认识，也许到了核心的一个水平。随意发布一个替代解决方案，其中 $message 可以是字符串。
最佳解决方案
以下版本的 wp_mail()在票证 https://core.trac.wordpress.org/ticket/15448 中应用了 @ rmccue / @ MattyRob 的修补程序，刷新了 4.2.2，这样可以使 $message 成为一个包含 content-type 键盘的数组：
/**
* Send mail, similar to PHP's mail
*
* A true return value does not automatically mean that the user received the
* email successfully. It just only means that the method used was able to
* process the request without any errors.
*
* Using the two 'wp_mail_from' and 'wp_mail_from_name' hooks allow from
* creating a from address like 'Name <email@address.com>' when both are set. If
* just 'wp_mail_from' is set, then just the email address will be used with no
* name.
*
* The default content type is 'text/plain' which does not allow using HTML.
* However, you can set the content type of the email by using the
* 'wp_mail_content_type' filter.
*
* If $message is an array, the key of each is used to add as an attachment
* with the value used as the body. The 'text/plain' element is used as the
* text version of the body, with the 'text/html' element used as the HTML
* version of the body. All other types are added as attachments.
*
* The default charset is based on the charset used on the blog. The charset can
* be set using the 'wp_mail_charset' filter.
*
* @since 1.2.1
*
* @uses PHPMailer
*
* @param string|array $to Array or comma-separated list of email addresses to send message.
* @param string $subject Email subject
* @param string|array $message Message contents
* @param string|array $headers Optional. Additional headers.
* @param string|array $attachments Optional. Files to attach.
* @return bool Whether the email contents were sent successfully.
*/
function wp_mail( $to, $subject, $message, $headers = '', $attachments = array() ) {
// Compact the input, apply the filters, and extract them back out
/**
* Filter the wp_mail() arguments.
*
* @since 2.2.0
*
* @param array $args A compacted array of wp_mail() arguments, including the "to" email,
* subject, message, headers, and attachments values.
*/
$atts = apply_filters( 'wp_mail', compact( 'to', 'subject', 'message', 'headers', 'attachments' ) );
if ( isset( $atts['to'] ) ) {
$to = $atts['to'];
}
if ( isset( $atts['subject'] ) ) {
$subject = $atts['subject'];
}
if ( isset( $atts['message'] ) ) {
$message = $atts['message'];
}
if ( isset( $atts['headers'] ) ) {
$headers = $atts['headers'];
}
if ( isset( $atts['attachments'] ) ) {
$attachments = $atts['attachments'];
}
if ( ! is_array( $attachments ) ) {
$attachments = explode( "n", str_replace( "rn", "n", $attachments ) );
}
global $phpmailer;
// (Re)create it, if it's gone missing
if ( ! ( $phpmailer instanceof PHPMailer ) ) {
require_once ABSPATH . WPINC . '/class-phpmailer.php';
require_once ABSPATH . WPINC . '/class-smtp.php';
$phpmailer = new PHPMailer( true );
}
// Headers
if ( empty( $headers ) ) {
$headers = array();
} else {
if ( !is_array( $headers ) ) {
// Explode the headers out, so this function can take both
// string headers and an array of headers.
$tempheaders = explode( "n", str_replace( "rn", "n", $headers ) );
} else {
$tempheaders = $headers;
}
$headers = array();
$cc = array();
$bcc = array();
// If it's actually got contents
if ( !empty( $tempheaders ) ) {
// Iterate through the raw headers
foreach ( (array) $tempheaders as $header ) {
if ( strpos($header, ':') === false ) {
if ( false !== stripos( $header, 'boundary=' ) ) {
$parts = preg_split('/boundary=/i', trim( $header ) );
$boundary = trim( str_replace( array( "'", '"' ), '', $parts[1] ) );
}
continue;
}
// Explode them out
list( $name, $content ) = explode( ':', trim( $header ), 2 );
// Cleanup crew
$name = trim( $name );
$content = trim( $content );
switch ( strtolower( $name ) ) {
// Mainly for legacy -- process a From: header if it's there
case 'from':
$bracket_pos = strpos( $content, '<' );
if ( $bracket_pos !== false ) {
// Text before the bracketed email is the "From" name.
if ( $bracket_pos > 0 ) {
$from_name = substr( $content, 0, $bracket_pos - 1 );
$from_name = str_replace( '"', '', $from_name );
$from_name = trim( $from_name );
}
$from_email = substr( $content, $bracket_pos + 1 );
$from_email = str_replace( '>', '', $from_email );
$from_email = trim( $from_email );
// Avoid setting an empty $from_email.
} elseif ( '' !== trim( $content ) ) {
$from_email = trim( $content );
}
break;
case 'content-type':
if ( is_array($message) ) {
// Multipart email, ignore the content-type header
break;
}
if ( strpos( $content, ';' ) !== false ) {
list( $type, $charset_content ) = explode( ';', $content );
$content_type = trim( $type );
if ( false !== stripos( $charset_content, 'charset=' ) ) {
$charset = trim( str_replace( array( 'charset=', '"' ), '', $charset_content ) );
} elseif ( false !== stripos( $charset_content, 'boundary=' ) ) {
$boundary = trim( str_replace( array( 'BOUNDARY=', 'boundary=', '"' ), '', $charset_content ) );
$charset = '';
}
// Avoid setting an empty $content_type.
} elseif ( '' !== trim( $content ) ) {
$content_type = trim( $content );
}
break;
case 'cc':
$cc = array_merge( (array) $cc, explode( ',', $content ) );
break;
case 'bcc':
$bcc = array_merge( (array) $bcc, explode( ',', $content ) );
break;
default:
// Add it to our grand headers array
$headers[trim( $name )] = trim( $content );
break;
}
}
}
}
// Empty out the values that may be set
$phpmailer->ClearAllRecipients();
$phpmailer->ClearAttachments();
$phpmailer->ClearCustomHeaders();
$phpmailer->ClearReplyTos();
$phpmailer->Body= '';
$phpmailer->AltBody= '';
// From email and name
// If we don't have a name from the input headers
if ( !isset( $from_name ) )
$from_name = 'WordPress';
/* If we don't have an email from the input headers default to wordpress@$sitename
* Some hosts will block outgoing mail from this address if it doesn't exist but
* there's no easy alternative. Defaulting to admin_email might appear to be another
* option but some hosts may refuse to relay mail from an unknown domain. See
* https://core.trac.wordpress.org/ticket/5007.
*/
if ( !isset( $from_email ) ) {
// Get the site domain and get rid of www.
$sitename = strtolower( $_SERVER['SERVER_NAME'] );
if ( substr( $sitename, 0, 4 ) == 'www.' ) {
$sitename = substr( $sitename, 4 );
}
$from_email = 'wordpress@' . $sitename;
}
/**
* Filter the email address to send from.
*
* @since 2.2.0
*
* @param string $from_email Email address to send from.
*/
$phpmailer->From = apply_filters( 'wp_mail_from', $from_email );
/**
* Filter the name to associate with the "from" email address.
*
* @since 2.3.0
*
* @param string $from_name Name associated with the "from" email address.
*/
$phpmailer->FromName = apply_filters( 'wp_mail_from_name', $from_name );
// Set destination addresses
if ( !is_array( $to ) )
$to = explode( ',', $to );
foreach ( (array) $to as $recipient ) {
try {
// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
$recipient_name = '';
if( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
if ( count( $matches ) == 3 ) {
$recipient_name = $matches[1];
$recipient = $matches[2];
}
}
$phpmailer->AddAddress( $recipient, $recipient_name);
} catch ( phpmailerException $e ) {
continue;
}
}
// If we don't have a charset from the input headers
if ( !isset( $charset ) )
$charset = get_bloginfo( 'charset' );
// Set the content-type and charset
/**
* Filter the default wp_mail() charset.
*
* @since 2.3.0
*
* @param string $charset Default email charset.
*/
$phpmailer->CharSet = apply_filters( 'wp_mail_charset', $charset );
// Set mail's subject and body
$phpmailer->Subject = $subject;
if ( is_string($message) ) {
$phpmailer->Body = $message;
// Set Content-Type and charset
// If we don't have a content-type from the input headers
if ( !isset( $content_type ) )
$content_type = 'text/plain';
/**
* Filter the wp_mail() content type.
*
* @since 2.3.0
*
* @param string $content_type Default wp_mail() content type.
*/
$content_type = apply_filters( 'wp_mail_content_type', $content_type );
$phpmailer->ContentType = $content_type;
// Set whether it's plaintext, depending on $content_type
if ( 'text/html' == $content_type )
$phpmailer->IsHTML( true );
// For backwards compatibility, new multipart emails should use
// the array style $message. This never really worked well anyway
if ( false !== stripos( $content_type, 'multipart' ) && ! empty($boundary) )
$phpmailer->AddCustomHeader( sprintf( "Content-Type: %s;nt boundary="%s"", $content_type, $boundary ) );
}
elseif ( is_array($message) ) {
foreach ($message as $type => $bodies) {
foreach ((array) $bodies as $body) {
if ($type === 'text/html') {
$phpmailer->Body = $body;
}
elseif ($type === 'text/plain') {
$phpmailer->AltBody = $body;
}
else {
$phpmailer->AddAttachment($body, '', 'base64', $type);
}
}
}
}
// Add any CC and BCC recipients
if ( !empty( $cc ) ) {
foreach ( (array) $cc as $recipient ) {
try {
// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
$recipient_name = '';
if( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
if ( count( $matches ) == 3 ) {
$recipient_name = $matches[1];
$recipient = $matches[2];
}
}
$phpmailer->AddCc( $recipient, $recipient_name );
} catch ( phpmailerException $e ) {
continue;
}
}
}
if ( !empty( $bcc ) ) {
foreach ( (array) $bcc as $recipient) {
try {
// Break $recipient into name and address parts if in the format "Foo <bar@baz.com>"
$recipient_name = '';
if( preg_match( '/(.*)<(.+)>/', $recipient, $matches ) ) {
if ( count( $matches ) == 3 ) {
$recipient_name = $matches[1];
$recipient = $matches[2];
}
}
$phpmailer->AddBcc( $recipient, $recipient_name );
} catch ( phpmailerException $e ) {
continue;
}
}
}
// Set to use PHP's mail()
$phpmailer->IsMail();
// Set custom headers
if ( !empty( $headers ) ) {
foreach ( (array) $headers as $name => $content ) {
$phpmailer->AddCustomHeader( sprintf( '%1$s: %2$s', $name, $content ) );
}
}
if ( !empty( $attachments ) ) {
foreach ( $attachments as $attachment ) {
try {
$phpmailer->AddAttachment($attachment);
} catch ( phpmailerException $e ) {
continue;
}
}
}
/**
* Fires after PHPMailer is initialized.
*
* @since 2.2.0
*
* @param PHPMailer &$phpmailer The PHPMailer instance, passed by reference.
*/
do_action_ref_array( 'phpmailer_init', array( &$phpmailer ) );
// Send!
try {
return $phpmailer->Send();
} catch ( phpmailerException $e ) {
return false;
}
}
所以如果你把它放在你的例子 「wp-content / mu-plugins / functions.php」 文件中，那么它将覆盖 WP 版本。它有一个很好的用法，没有任何混乱的标题，例如：
// Set $to to an hotmail.com or outlook.com email
$to = "YourEmail@hotmail.com";
$subject = 'wp_mail testing multipart';
$message['text/plain'] = 'Hello world! This is plain text...';
$message['text/html'] = '<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<p>Hello World! This is HTML...</p>
</body>
</html>';
add_filter( 'wp_mail_from', $from_func = function ( $from_email ) { return 'foo@bar.com'; } );
add_filter( 'wp_mail_from_name', $from_name_func = function ( $from_name ) { return 'Foo'; } );
// send email
wp_mail( $to, $subject, $message );
remove_filter( 'wp_mail_from', $from_func );
remove_filter( 'wp_mail_from_name', $from_name_func );
请注意，我没有用实际的电子邮件测试这个…
参考文献
注：本文内容整合自 Google/Baidu/Bing 辅助翻译的英文资料结果。如果您对结果不满意，可以加入我们改善翻译效果：薇晓朵技术论坛。