.txt file attachments ignored

Mailhandler ignores .txt attachments. In MailhandlerPhpImapRetrieve.class.php in the function get_parts, this block of code:

// Handle Content-Disposition parameters for non-text types.
    if ($structure->type != TYPETEXT && $structure->ifdparameters) {
      foreach ($structure->dparameters as $parameter) {
        switch (drupal_strtoupper($parameter->attribute)) {
          case 'NAME':
          case 'FILENAME':
            $part->filename = $parameter->value;
            break;
          // put every thing else in the attributes array;
          default:
            $part->attributes[$parameter->attribute] = $parameter->value;
        }
      }
    }

get skipped on .txt files. this means they never get named, and thus not saved (I believe). Retrieving the same file renamed with a different extension works fine. I'm not sure what the best fix is. I assume simply removing the condition will have unintended consequences.

The email was sent on linux using:
mutt -s "1bfdf" -a letter.txt -- admin-zEZ488f8zZ@mothership < letter2.txt

Here is my feed importer:

$feeds_importer = new stdClass;
$feeds_importer->disabled = FALSE; /* Edit this to true to make a default feeds_importer disabled initially */
$feeds_importer->api_version = 1;
$feeds_importer->id = 'feed_importer_2';
$feeds_importer->config = array(
  'name' => 'Feed Importer 2',
  'description' => 'Feed Importer 2',
  'fetcher' => array(
    'plugin_key' => 'MailhandlerFetcher',
    'config' => array(
      'filter' => 'MailhandlerFiltersNodes',
    ),
  ),
  'parser' => array(
    'plugin_key' => 'MailhandlerParser',
    'config' => array(
      'default_commands' => 'status: 1',
      'commands_failed_auth' => 'status: 0',
      'available_commands' => 'status',
      'command_plugin' => array(
        'MailhandlerCommandsHeaders' => 'MailhandlerCommandsHeaders',
        'MailhandlerCommandsDefault' => 'MailhandlerCommandsDefault',
        'MailhandlerCommandsFiles' => 'MailhandlerCommandsFiles',
      ),
      'authenticate_plugin' => 'MailhandlerAuthenticateTokenauth',
    ),
  ),
  'processor' => array(
    'plugin_key' => 'FeedsNodeProcessor',
    'config' => array(
      'content_type' => 'story',
      'input_format' => '0',
      'update_existing' => '0',
      'expire' => '-1',
      'mappings' => array(
        0 => array(
          'source' => 'subject',
          'target' => 'title',
          'unique' => FALSE,
        ),
        1 => array(
          'source' => 'body_html',
          'target' => 'body',
          'unique' => FALSE,
        ),
        2 => array(
          'source' => 'authenticated_uid',
          'target' => 'uid',
          'unique' => FALSE,
        ),
        3 => array(
          'source' => 'date',
          'target' => 'created',
          'unique' => FALSE,
        ),
        4 => array(
          'source' => 'attachments',
          'target' => 'attachment_field',
          'unique' => FALSE,
        ),
        5 => array(
          'source' => 'udate',
          'target' => 'created',
          'unique' => FALSE,
        ),
      ),
      'author' => 0,
      'authorize' => 0,
    ),
  ),
  'content_type' => 'mailhandler_source',
  'update' => 0,
  'import_period' => '0',
  'expire_period' => 3600,
  'import_on_create' => 1,
);