Lately I updated the Ubuntu 12.04 where I run Zimbra 8.x and found that the log file of ‘clamd’ process was filling incredibly fast with the follwoing error line and the emails received’s subject were tagged with ‘**UNCHECKED**’
LibClamAV Error: mpool_malloc(): Attempt to allocate 8388608 bytes. Please report to
Finally I found a solution at this post:**UNCHECKED**_in_all_messages
The solution was to upgrade Zimbra or to disable the Anti-virus from Zimbra with the following commands run a ‘zimbra’ user:
zmprov ms `zmhostname` -zimbraServiceEnabled antivirus
zmcontrol restart

After this the following process of clamd wasn’t present any more and that is good news.
/opt/zimbra/clamav/sbin/clamd --config-file=/opt/zimbra/conf/clamd.conf

That worked and now I have no Antivirus in Zimbra but for now I don’t need it.