==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.7
- Linux/BSD distribution name and version: Centos 7.4
- 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.
====

First of all, I would like to say thank you for this amazing software.
I have been running iRedmail server for a few months without a problem. Recently I upgraded centos 7.4 from 7.3 with yum update. No problem with email so far. But I have some errors showing in logwatch email.

1.
--------------------- Clamav Begin ------------------------

Virus database reloaded 4 time(s) (last time with 6379631 viruses)

**Unmatched Entries**
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/main.cvd and /var/lib/clamav/main.cld. The /var/lib/clamav/main.cvd database is older and will not be loaded, you should manually remove it from the database directory.
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/bytecode.cvd and /var/lib/clamav/bytecode.cld. The /var/lib/clamav/bytecode.cvd database is older and will not be loaded, you should manually remove it from the database directory.
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/main.cvd and /var/lib/clamav/main.cld. The /var/lib/clamav/main.cvd database is older and will not be loaded, you should manually remove it from the database directory.
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/bytecode.cvd and /var/lib/clamav/bytecode.cld. The /var/lib/clamav/bytecode.cvd database is older and will not be loaded, you should manually remove it from the database directory.
Limits: MaxEmbeddedPE limit set to 10485760 bytes.
Limits: MaxHTMLNormalize limit set to 10485760 bytes.
Limits: MaxHTMLNoTags limit set to 2097152 bytes.
Limits: MaxScriptNormalize limit set to 5242880 bytes.
Limits: MaxZipTypeRcg limit set to 1048576 bytes.
Limits: MaxPartitions limit set to 50.
Limits: MaxIconsPE limit set to 100.
Limits: MaxRecHWP3 limit set to 16.
Limits: PCREMatchLimit limit set to 10000.
Limits: PCRERecMatchLimit limit set to 5000.
Limits: PCREMaxFileSize limit set to 26214400.
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/main.cvd and /var/lib/clamav/main.cld. The /var/lib/clamav/main.cvd database is older and will not be loaded, you should manually remove it from the database directory.
LibClamAV Warning: Detected duplicate databases /var/lib/clamav/bytecode.cvd and /var/lib/clamav/bytecode.cld. The /var/lib/clamav/bytecode.cvd database is older and will not be loaded, you should manually remove it from the database directory.
Limits: MaxEmbeddedPE limit set to 10485760 bytes.
Limits: MaxHTMLNormalize limit set to 10485760 bytes.
Limits: MaxHTMLNoTags limit set to 2097152 bytes.
Limits: MaxScriptNormalize limit set to 5242880 bytes.
Limits: MaxZipTypeRcg limit set to 1048576 bytes.
Limits: MaxPartitions limit set to 50.
Limits: MaxIconsPE limit set to 100.
Limits: MaxRecHWP3 limit set to 16.
Limits: PCREMatchLimit limit set to 10000.
Limits: PCRERecMatchLimit limit set to 5000.
Limits: PCREMaxFileSize limit set to 26214400.

---------------------- Clamav End -------------------------

Should I remove main.cvd like suggested ?

2.
--------------------- Connections (secure-log) Begin ------------------------

New Groups:
    virusgroup (990)

Added User to group:
    virusgroup:
       clamupdate

**Unmatched Entries**
    polkitd: Acquired the name org.freedesktop.PolicyKit1 on the system bus: 2 Time(s)
    polkitd: Finished loading, compiling and executing 2 rules: 2 Time(s)
    polkitd: Loading rules from directory /etc/polkit-1/rules.d: 2 Time(s)
    polkitd: Loading rules from directory /usr/share/polkit-1/rules.d: 2 Time(s)
    polkitd: Registered Authentication Agent for unix-process:23225:1390539535 (system bus name :1.59092 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_GB.UTF-8): 1 Time(s)
    useradd: failed adding user 'apache', exit code: 9: 1 Time(s)
    useradd: failed adding user 'mysql', exit code: 9: 1 Time(s)
    usermod: add 'clamupdate' to shadow group 'virusgroup': 1 Time(s)

---------------------- Connections (secure-log) End -------------------------

Adding 'clamupdate' to shadow group 'virtusgroup' ? I didn't do this command. Is that automated command by clamupdate?
Should I be worry? I'm new to linux server.
Many thanks.