MIME-encoded mail headers not decoded

My site is set up to import e-mails into nodes, placing the From, Reply-To and Subject headers into CCK fields.
I recently received an e-mail where all three of these headers were MIME-Encoded (e.g. "=?utf-8?q?Hello_World?=" instead of "Hello World"). I was pleasantly surprised to see that the Subject header was correctly decoded in the node that was created, but puzzled that the From and Reply-To headers were not.

After looking into mailhandler's code, I found the following in mailhandler/plugins/mailhandler/commands/MailhandlerCommandsHeaders.class.php, inside the loop that parses each line of the header in the function process():

        if (in_array($key, array('Subject', 'subject'))) {
          $message[$key] = iconv_mime_decode($value, 0, "UTF-8");
        }
        else {
          $message[$key] = $value;
        }

This code clearly explains the behaviour I'm seeing. Is there any reason why only the subject header is MIME-decoded, and not the other headers? Changing the code to the following has fixed the problem I was seeing, but I'm not sure if MIME-decoding should be applied to all headers, or selectively. This change only includes the headers I needed for my site, but, for example, the "To" header in the e-mail in question was also MIME-encoded, so should really be dealt with like this as well. I'm not sure which other headers would also need MIME-decoding.

        if (in_array($key, array('Subject', 'subject', 'fromaddress', 'reply_toaddress'))) {
          $message[$key] = iconv_mime_decode($value, 0, "UTF-8");
        } else if (in_array($key, array('from', 'reply_to'))) {
          $message[$key] = array();
          foreach ($value as $array_key => $array_object) {
            $array_object->personal = iconv_mime_decode($array_object->personal, 0, "UTF-8");
            $message[$key][$array_key] = $array_object;
          }
        } else {
          $message[$key] = $value;
        }

A patch with this change (against 6.x-2.4) is attached; as far as I can see this should apply to 6.x-2.x-dev and 7.x-2.x-dev as well.