I have installed a Zimbra OSE 8.0.2 on Ubuntu 12.04 and would like to install postgrey.

But after installing postgrey is unable to start.

zimbra.log
Code:
postfix/sendmail[15760]: fatal: open /etc/postfix/main.cf: No such file or directory
master[16412]: fatal: master_spawn: exec /opt/zimbra/postfix/libexec/smtpd: No such file or directory
sshd[16413]: Accepted publickey for nagios from 172.24.128.40 port 49334 ssh2
postfix/master[3632]: warning: process /opt/zimbra/postfix/libexec/smtpd pid 16412 exit status 1
postfix/master[3632]: warning: /opt/zimbra/postfix/libexec/smtpd: bad command startup -- throttling