Load headers eagerly to avoid re-encoding problems with multivalve headers

src/Headers.php

@@ -228,7 +228,11 @@ public function addHeaderLine($headerFieldNameOrLine, $fieldValue = null)
         }
 
         if ($fieldValue === null) {
-            $this->addHeader(Header\GenericHeader::fromString($headerFieldNameOrLine));
+            $headers = $this->loadHeader($headerFieldNameOrLine);
+            $headers = is_array($headers) ? $headers : [$headers];
+            foreach ($headers as $header) {
+                $this->addHeader($header);
+            }
         } elseif (is_array($fieldValue)) {
             foreach ($fieldValue as $i) {
                 $this->addHeader(Header\GenericMultiHeader::fromString($headerFieldNameOrLine . ':' . $i));
@@ -465,6 +469,21 @@ public function forceLoading()
         return true;
     }
 
+    /**
+     * Create Header object from header line
+     *
+     * @param string $headerLine
+     * @return \Zend\Mail\Header\HeaderInterface
+     */
+    public function loadHeader($headerLine)
+    {
+        list($name, ) = \Zend\Mail\Header\GenericHeader::splitHeaderLine($headerLine);
+
+        $class = ($this->getPluginClassLoader()->load($name)) ?: 'Zend\Mail\Header\GenericHeader';
+
+        return $class::fromString($headerLine);
+    }
+
     /**
      * @param $index
      * @return mixed

test/Storage/MessageTest.php

@@ -9,12 +9,12 @@
 
 namespace ZendTest\Mail\Storage;
 
-use Zend\Mime;
-use Zend\Mime\Exception as MimeException;
 use Zend\Mail\Exception as MailException;
 use Zend\Mail\Storage;
 use Zend\Mail\Storage\Exception;
 use Zend\Mail\Storage\Message;
+use Zend\Mime;
+use Zend\Mime\Exception as MimeException;
 
 /**
  * @group      Zend_Mail
@@ -23,10 +23,12 @@
 class MessageTest extends \PHPUnit_Framework_TestCase
 {
     protected $_file;
+    protected $_file2;
 
     public function setUp()
     {
         $this->_file = __DIR__ . '/../_files/mail.txt';
+        $this->_file2 = __DIR__ . '/../_files/mail_multi_to.txt';
     }
 
     public function testInvalidFile()
@@ -430,6 +432,16 @@ public function testStrictParseMessage()
         $message = new Message(['raw' => $raw, 'strict' => true]);
     }
 
+    public function testMultivalueToHeader()
+    {
+        $message = new Message(['file' => $this->_file2]);
+        /** @var \Zend\Mail\Header\To $header */
+        $header = $message->getHeader('to');
+        $addressList = $header->getAddressList();
+        $this->assertEquals(2, $addressList->count());
+        $this->assertEquals('nicpoń', $addressList->get('bar@example.pl')->getName());
+    }
+
     public function filesProvider()
     {
         $filePath = __DIR__ . '/../_files/mail.txt';

test/_files/mail_multi_to.txt

@@ -0,0 +1,11 @@
+Return-Path: <sender@example.com>
+Date: Sun, 01 Jan 2000 00:00:00 +0000
+From: sender@example.com
+To: =?ISO-8859-2?Q?nicpo=F1?= <bar@example.pl>, "foo" <foo@example.pl>
+Subject: Subject text
+Content-Type: text/html; charset=iso-8859-2
+Content-Transfer-Encoding: 8bit
+Content-Disposition: inline
+
+<div>html content</div>
+