dead.letter

[Amney]

Hello!
What is this file in the root of the server?

Here its contents:

Date: Thu, 28 Jan 2016 04:56:15 +0300
To: root@localhost
Subject: rkhunter Daily Run on serverfree
User-Agent: Heirloom mailx 12.4 7/29/08
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit


--------------------- Start Rootkit Hunter Update ---------------------
[ Rootkit Hunter version 1.4.2 ]

Checking rkhunter data files...
  Checking file mirrors.dat                                  [ No update ]
  Checking file programs_bad.dat                             [ No update ]
  Checking file backdoorports.dat                            [ No update ]
  Checking file suspscan.dat                                 [ No update ]
  Checking file i18n/cn                                      [ No update ]
  Checking file i18n/de                                      [ No update ]
  Checking file i18n/en                                      [ No update ]
  Checking file i18n/tr                                      [ No update ]
  Checking file i18n/tr.utf8                                 [ No update ]
  Checking file i18n/zh                                      [ No update ]
  Checking file i18n/zh.utf8                                 [ No update ]

---------------------- Start Rootkit Hunter Scan ----------------------
Warning: Checking for prerequisites               [ Warning ]
         The file of stored file properties (rkhunter.dat) does not exist, and should be created. To do this type in 'rkhunter --propupd'.
Warning: WARNING! It is the users responsibility to ensure that when the '--propupd' option
         is used, all the files on their system are known to be genuine, and installed from a
         reliable source. The rkhunter '--check' option will compare the current file properties
         against previously stored values, and report if any values differ. However, rkhunter
         cannot determine what has caused the change, that is for the user to do.
Warning: User 'alias' has been removed from the passwd file.
Warning: User 'qmaild' has been removed from the passwd file.
Warning: User 'qmaill' has been removed from the passwd file.
Warning: User 'qmailp' has been removed from the passwd file.
Warning: User 'qmailq' has been removed from the passwd file.
Warning: User 'qmailr' has been removed from the passwd file.
Warning: User 'qmails' has been removed from the passwd file.
Warning: Changes found in the passwd file for user 'vpopmail':
Warning: Group 'nofiles' has been removed from the group file.
Warning: Group 'qmail' has been removed from the group file.
Warning: Changes found in the group file for group 'vchkpw':

----------------------- End Rootkit Hunter Scan -----------------------