? properly_formatted_mail_return_path_d6.patch
Index: includes/mail.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/mail.inc,v
retrieving revision 1.8.2.7
diff -u -p -r1.8.2.7 mail.inc
--- includes/mail.inc	18 Jun 2009 12:15:44 -0000	1.8.2.7
+++ includes/mail.inc	8 Mar 2010 08:38:22 -0000
@@ -122,6 +122,16 @@ function drupal_mail($module, $key, $to,
   // Invoke hook_mail_alter() to allow all modules to alter the resulting e-mail.
   drupal_alter('mail', $message);
 
+  // If 'Return-Path' isn't already set in php.ini, we pass it separately as an
+  // additional parameter instead of in the header.
+  if (isset($message['headers']['Return-Path']) && !ini_get('safe_mode')) {
+    $return_path_set = strpos(ini_get('sendmail_path'), ' -f');
+    if (!$return_path_set) {
+      $message['Return-Path'] = $message['headers']['Return-Path'];
+      unset($message['headers']['Return-Path']);
+    }
+  }
+
   // Concatenate and wrap the e-mail body.
   $message['body'] = is_array($message['body']) ? drupal_wrap_mail(implode("\n\n", $message['body'])) : drupal_wrap_mail($message['body']);
 
@@ -181,16 +191,38 @@ function drupal_mail_send($message) {
     foreach ($message['headers'] as $name => $value) {
       $mimeheaders[] = $name .': '. mime_header_encode($value);
     }
-    return mail(
-      $message['to'],
-      mime_header_encode($message['subject']),
-      // Note: e-mail uses CRLF for line-endings, but PHP's API requires LF.
-      // They will appear correctly in the actual e-mail that is sent.
-      str_replace("\r", '', $message['body']),
-      // For headers, PHP's API suggests that we use CRLF normally,
-      // but some MTAs incorrecly replace LF with CRLF. See #234403.
-      join("\n", $mimeheaders)
-    );
+
+    // Prepare mail commands.
+    $mail_subject = mime_header_encode($message['subject']);
+    // Note: e-mail uses CRLF for line-endings, but PHP's API requires LF.
+    // They will appear correctly in the actual e-mail that is sent.
+    $mail_body = str_replace("\r", '', $message['body']);
+    // For headers, PHP's API suggests that we use CRLF normally,
+    // but some MTAs incorrecly replace LF with CRLF. See #234403.
+    $mail_headers = join("\n", $mimeheaders);
+
+    if (isset($message['Return-Path']) && !ini_get('safe_mode')) {
+      $mail_result = mail(
+        $message['to'],
+        $mail_subject,
+        $mail_body,
+        $mail_headers,
+        // Pass the Return-Path via sendmail's -f command.
+        '-f ' . $message['Return-Path']
+      );
+    }
+    else {
+      // The optional $additional_parameters argument to mail() is not allowed
+      // if safe_mode is enabled. Passing any value throws a PHP warning and
+      // makes mail() return FALSE.
+      $mail_result = mail(
+        $message['to'],
+        $mail_subject,
+        $mail_body,
+        $mail_headers
+      );
+    }
+    return $mail_result;
   }
 }