問題描述
總結
由於 WP Core 中存在錯誤，因此使用 wp_mail()傳送 multipart 電子郵件 (html / text)(以減少垃圾郵件資料夾中的電子郵件結果的可能性)，會導致您的域被 Hotmail(和其他 Microsoft 電子郵件) 阻止。
這是一個複雜的問題，我將致力於細細分解，以試圖幫助某人找到可能最終在核心中實現的可行解決方案。
這將是一個有益的閱讀。讓我們開始…
錯誤
最常見的建議是避免將通訊電子郵件最終傳送到垃圾郵件資料夾中，是傳送多部分訊息。
Multi-part(mime) 是指在單個電子郵件中傳送電子郵件的 HTML 和 TEXT 部分。當客戶端收到多部分訊息時，它接受 HTML 版本，如果它可以呈現 HTML，否則它會顯示純文字版本。
這被證明是有效的。傳送到 Gmail 時，我們的所有電子郵件都將登陸垃圾郵件資料夾，直到我們將郵件更改為 multipart，當他們進入主收件箱時。好東西。
現在，當透過 wp_mail() 傳送多部分訊息時，它會輸出內容型別 (multipart / *) 兩次，一次使用邊界 (如果自定義)，一次不會。這種行為導致電子郵件顯示為原始郵件，而不是在某些電子郵件中展示，包括所有 Microsoft(Hotmail，Outlook 等)
微軟將此郵件標記為垃圾郵件，並且透過的幾條郵件將被收件人手動標記。不幸的是，Microsoft 電子郵件地址被廣泛使用。我們 40％的使用者使用它。
這是微軟透過我們最近透過電子郵件交換確認的。
郵件的標記將導致域被完全阻止。這意味著郵件不會傳送到垃圾郵件資料夾，甚至不會將郵件傳送到收件人。
到目前為止，我們的主要域名已經被阻止了 3 次。
因為這是 WP 核心中的一個錯誤，所以傳送多部分訊息的每個域都被阻止。問題是大多數網站管理員不知道為什麼。我在進行研究和檢視其他使用者在論壇上討論這個問題時已經證實了這一點。它需要深入瞭解原始程式碼，並且很好地瞭解這些型別的電子郵件的工作原理，我們將要下一步…
我們把它分解成程式碼
建立一個 hotmail / outlook 帳戶。然後，執行以下程式碼：
// 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，請使用：
add_filter( 'wp_mail_content_type', 'set_content_type' );
function set_content_type( $content_type ) {
return 'multipart/alternative';
}
這將傳送一個多部分訊息。
因此，如果您檢視訊息的完整原始來源，您會注意到內容型別被新增了兩次，一次沒有邊界：
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="====f230673f9d7c359a81ffebccb88e5d61=="
MIME-Version: 1.0
Content-Type: multipart/alternative; charset=
這是問題。
問題的根源在於 pluggable.php – 如果我們在這裡看到某處：
// 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;
}
}
}
潛在的解決方案
所以你想知道，為什麼你沒有在 trac 報告？我 already have 。令我驚奇的是，different ticket 是在 5 年前建立的，它概述了同樣的問題。
我們來面對現在，已經過了半個十年。在網際網路年代，這更像是 30. 這個問題已經被明確地放棄了，基本上永遠不會被修改 (除非我們在這裡解決) 。
我發現一個偉大的 thread here 提供了一個解決方案，但是當他的解決方案工作時，它會打破沒有自定義 $headers 設定的電子郵件。
這就是我們每次崩潰的地方。多部分版本都能正常工作，並且正常未設定的 $headers 訊息不會被修改，也不能修改。
我們提出的解決辦法是：
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，編輯核心檔案是禁忌的，請坐下來… 這是一個絕望的修復，並且嘗試提供一個核心的修復。
我們修復的問題是，預設電子郵件，如新註冊，註釋，密碼重置等將作為空白訊息傳遞。所以我們有一個 working wp_mail() 指令碼將傳送多部分訊息，但沒有別的。
該怎麼辦
這裡的目的是找到一種使用 core wp_mail() 函式 (而不是自定義 sendmail 函式) 傳送普通 (純文字) 和多部分訊息的方法。
當您嘗試解決這個問題時，您將遇到的主要問題是您花費在傳送虛擬訊息的時間，檢查是否收到，並且基本上開啟一盒阿司匹林並詛咒 Microsoft，因為您習慣了他們 IE 問題，而這裡的 gremlin 不幸的是 WordPress 。
Update
@bonger 釋出的解決方案允許 $message 是一個包含 content-type 鍵控的陣列的陣列。我已經確認它在所有情況下都有效。
我們將允許這個問題保持開放，直到獲得充足的利益來提高對這個問題的認識，也許到了核心的一個水平。隨意釋出一個替代解決方案，其中 $message 可以是字串。
最佳解決方案
以下版本的 wp_mail()在票證 https://core.trac.wordpress.org/ticket/15448 中應用了 @ rmccue / @ MattyRob 的修補程式，重新整理了 4.2.2，這樣可以使 $message 成為一個包含 content-type 鍵盤的陣列：
/**
* 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」 檔案中，那麼它將覆蓋 WP 版本。它有一個很好的用法，沒有任何混亂的標題，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 );
請注意，我沒有用實際的電子郵件測試這個…
參考文獻
注：本文內容整合自 Google/Baidu/Bing 輔助翻譯的英文資料結果。如果您對結果不滿意，可以加入我們改善翻譯效果：薇曉朵技術論壇。