如何解码imap 7bit编码消息？

Question

我只是使用以下代码对7bit编码的消息进行解码。它正在处理某些消息，但有些消息显示仍然显示加密的encrypted.some消息。如何正确解码此消息？有人请帮帮我。

   public function decode7Bit($text) {

    // actually base64-encoded, and decode it.      
    if($this->_isEncodedBase64($text)){
        $text = base64_decode($text);
    } 


    // Manually convert common encoded characters into their UTF-8 equivalents.
    $characters = array(
                 '=20' => ' ', // space.
                 '=E2=80=99' => "'", // single quote.
                 '=0A' => "\r\n", // line break.
                 '=A0' => ' ', // non-breaking space.
                 '=C2=A0' => ' ', // non-breaking space.
                 "=\r\n" => '', // joined line.
                 '=E2=80=A6' => '…', // ellipsis.
                 '=E2=80=A2' => '•', // bullet.
    );

    // Loop through the encoded characters and replace any that     are found.
    foreach ($characters as $key => $value) {
        $text = str_replace($key, $value, $text);
    }
    return $text;
   }

   private function _isEncodedBase64($data){

    if ( base64_encode(base64_decode($data)) === $data){
        return true;
    }

    return false;
   }

  $body = imap_fetchbody($inbox, $messageId, 1.2);
  if (!strlen($body) > 0) {
    $body = imap_fetchbody($inbox, $messageId, 1);
  }
  // Get the raw headers.
  $raw_header = imap_fetchheader($inbox, $messageId);

  // Get the message body.
  $body = imap_fetchbody($inbox, $messageId, 1.2);
  if (!strlen($body) > 0) {
    $body = imap_fetchbody($inbox, $messageId, 1);
  }
 //  print_r($body);
  // Get the message body encoding.

   $encodings = array(
  0 => '7BIT',
  1 => '8BIT',
  2 => 'BINARY',
  3 => 'BASE64',
  4 => 'QUOTED-PRINTABLE',
  5 => 'OTHER',
);
// Get the structure of the message.
$structure = imap_fetchstructure($inbox, $messageId);
// Return a number or a string, depending on the $numeric value.
if ($numeric) {
  $encoding =$structure->encoding;
} else {
  $encoding= $encodings[$structure->encoding];
}

  // Decode body into plaintext (8bit, 7bit, and binary are exempt).
  if ($encoding == 'BASE64') {
    $body = imap_base64($body);
  }
  elseif ($encoding == 'QUOTED-PRINTABLE') {
    $body = quoted_printable_decode($body);
  }
  elseif ($encoding == '8BIT') {
    $body = quoted_printable_decode(imap_8bit($body));
  }
  elseif ($encoding == '7BIT') {
    $body = $this->decode7Bit($body);
  }
  else{
      $body = $body;
  }