I use to receive a dianiostic email as follow

Code:
from:   "Cron Daemon"   

subject: Cron  /opt/zimbra/libexec/zmdailyreport -m

message: bzip2: /var/log/zimbra.log-20100828.gz is not a bzip2 file.
Date, obviously, change day by day

I have just update to 6.0.8 with no problem but this happened also with 6.0.7

What can cause this annoying message?

Thank you

Best Regards,

Alex