==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.6
- Linux/BSD distribution name and version: FreeBSD 10.3-RELEASE Jail
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

i'm getting this message 10 minute intervals in postmaster@ mail account. What is this error? How can i fix this? Thanks.

Mail content is below.

The original message was received at Wed, 24 May 2017 14:10:06 +0300 (+03)
from root@localhost

   ----- The following addresses had permanent fatal errors -----
root
    (reason: 554 5.7.1 <root@mail.xxx.xxx.xx>: Recipient address rejected: Policy rejection not logged in)
    (expanded from: root)

   ----- Transcript of session follows -----
... while talking to [127.0.0.1]:

            DATA

<<< 554 5.7.1 <root@mail.xxx.xxx.xx>: Recipient address rejected: Policy rejection not logged in
554 5.0.0 Service unavailable
<<< 554 5.5.1 Error: no valid recipients
Reporting-MTA: dns; mail.xxx.xxx.xx
Arrival-Date: Wed, 24 May 2017 14:10:06 +0300 (+03)

Final-Recipient: RFC822; root@mail.xxx.xxx.xx
Action: failed
Status: 5.7.1
Remote-MTA: DNS; [127.0.0.1]
Diagnostic-Code: SMTP; 554 5.7.1 <root@mail.xxx.xxx.xx>: Recipient address rejected: Policy rejection not logged in
Last-Attempt-Date: Wed, 24 May 2017 14:10:06 +0300 (+03)
Subject     Cron <root@mail> /usr/local/bin/python /opt/iredapd/tools/spf_to_greylist_whitelists.py &>/dev/null
From     root
To     root
Date     Today 14:10
* Query SQL server to get mail domain names.
* No valid domain names, exit.