[exim] Some LDA questions

Hi there!
I have been setuped exim and dovecot.
Exim uses dovecot-lda to deliver mails to mailbox.

Some configurations of exim:

dovecot_virtual_delivery:
  driver = pipe
  command = /usr/libexec/dovecot/dovecot-lda -d $local_part@$domain -f $sender_address
  message_prefix =
  message_suffix =
  delivery_date_add
  envelope_to_add
  return_path_add
  log_output
  user = vmail
  group = vmail
  #mode = 0660
  temp_errors = 64 : 69 : 70: 71 : 72 : 73 : 74 : 75 : 78

dovecot does mysql lookups of users, passwords.
All works, but in headers of example message:

Return-path: <"vitalyf@???>
Envelope-to: vitalyf@???
Delivery-date: Tue, 11 Feb 2014 03:59:17 -0600
Received: from xxx.net ([11.22.33.44] helo=[192.168.1.77])
 by host.aaa.com with esmtpsa (TLS1.0:ECDHE_RSA_AES_128_CBC_SHA1:128)
 (Exim 4.82)
 (envelope-from <"vitalyf@???>)
 id 1WDA7Y-0007GS-VR
 for vitalyf@???; Tue, 11 Feb 2014 03:59:17 -0600
Message-ID: <52F9F468.9030001@???>
Date: Tue, 11 Feb 2014 16:59:04 +0700
From: =?UTF-8?B?0KTQsNC00LXQtdCyINCS0LjRgtCw0LvQuNC5INCb0YzQstC+0LLQuNGH?=
 <vitalyf@???>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0
MIME-Version: 1.0
To: vitalyf@???
Subject: adfasdf
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Sender: "vitalyf@???
Test headers
host.aaa.com is a hostname that run dovecot and exim.
bbb.com is a virtual domain located in mysql db.
I do not want to show host.aaa.com in headers. How can i disable this so headers looks like this:
Return-path: <vitalyf@???> Which configuration i need to show you?