Sudoers
The file /etc/sudoers lists users authorized to run certain commands as other users. Edit this file if necessary with the visudo command. You should see some lines like the following, though the versions of postfix and openldap should match what's on your system rather than what is here.
# grep zimbra /etc/sudoers %zimbra ALL=NOPASSWD:/opt/zimbra/openldap-2.3.21/libexec/slapd %zimbra ALL=NOPASSWD:/opt/zimbra/postfix-2.2.9/sbin/postfix, /opt/zimbra/postfix-2.2.9/sbin/postalias, /opt/zimbra/postfix-2.2.9/sbin/qshape.pl, /opt/zimbra/postfix-2.2.9/sbin/postconf,/opt/zimbra/postfix-2.2.9/sbin/postsuper %zimbra ALL=NOPASSWD:/opt/zimbra/libexec/zmqstat %zimbra ALL=NOPASSWD:/opt/zimbra/libexec/zmtomcatstart %zimbra ALL=NOPASSWD:/opt/zimbra/perdition/sbin/perdition
# ls -l /opt/zimbra/openldap /opt/zimbra/postfix lrwxrwxrwx 1 root root 27 May 9 14:23 /opt/zimbra/openldap -> /opt/zimbra/openldap-2.3.21 lrwxrwxrwx 1 root root 25 May 9 14:23 /opt/zimbra/postfix -> /opt/zimbra/postfix-2.2.9