C:\xampp\tmp\test1 (file C:\xampp\tmp\test1) is not in valid mailbox format

The quick-start module provides a test Mailbox and message, a default Importer,
and a Source content type. Try to import this test message now:
- Go to $base_url/admin/build/modules
- Enable the "Mailhandler quick-start" module.
- Go to $base_url/node/add/mailhandler-source
- Give the node a title (such as 'Test source').
- For "Feed"->"Mailbox", select the mailbox to import from.
- Saved the node.
Expected:
You should see the message 'created 1 story node'.

but got the error:
An AJAX HTTP error occurred. HTTP Result Code: 200 Debugging information follows. Path: /drupal7/batch?id=9&op=do StatusText: OK ResponseText: {"status":true,"percentage":"100","message":""} Notice: Undefined offset: 0 in C:\xampp\htdocs\drupal7\includes\errors.inc on line 271 Notice: Undefined index: file in C:\xampp\htdocs\drupal7\includes\errors.inc on line 72 Notice: Undefined index: line in C:\xampp\htdocs\drupal7\includes\errors.inc on line 73

However the node I was created but I assume that I shouldn't be seeing this error in the first time.

Copy of 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 = 'mailhandler_nodes';
$feeds_importer->config = array(
'name' => 'Mailhandler nodes',
'description' => 'Imports nodes from a Mailhandler mailbox',
'fetcher' => array(
'plugin_key' => 'MailhandlerFetcher',
'config' => array(
'filter' => 'MailhandlerFiltersNodes',
),
),
'parser' => array(
'plugin_key' => 'MailhandlerParser',
'config' => array(
'authenticate_plugin' => 'MailhandlerAuthenticateDefault',
'available_commands' => 'status',
),
),
'processor' => array(
'plugin_key' => 'FeedsNodeProcessor',
'config' => array(
'bundle' => 'article',
'expire' => '-1',
'author' => 0,
'mappings' => array(
0 => array(
'source' => 'subject',
'target' => 'title',
'unique' => FALSE,
),
1 => array(
'source' => 'authenticated_uid',
'target' => 'uid',
'unique' => FALSE,
),
2 => array(
'source' => 'status',
'target' => 'status',
'unique' => FALSE,
),
3 => array(
'source' => 'body_text',
'target' => 'body',
'unique' => FALSE,
),
4 => array(
'source' => 'message_id',
'target' => 'guid',
'unique' => 1,
),
),
'update_existing' => '0',
'input_format' => 'plain_text',
),
),
'content_type' => 'mailhandler_source',
'update' => 0,
'import_period' => '900',
'expire_period' => 3600,
'import_on_create' => 1,
'process_in_background' => 0,
);

I tried increasing the Import_period to 2700 but in vain
Any help?
And please do not close this issue as It is not a duplicate one.
In my db_logs, I get the error : Unable to connect to "test_mailbox". please check connection settings for this mailbox