I created a user postfix and placed it in the postfix group that Zimbra created . The error:
        Starting spell...FAILED
Syntax error on line 232 of /opt/zimbra/conf/httpd.conf:
Cannot load /opt/zimbra/httpd-2.0.54/modules/libphp5.so into server: /opt/zimbra/httpd-2.0.54/modules/libphp5.so: cannot restore segment prot after reloc: Permission denied
still occurs but I'll live without the spell checking.

However, I know get the error:
        Starting mta...FAILED
postsuper: fatal: scan_dir_push: open directory defer: Permission denied
postfix failed to start
I had done
chown zimbra -R /opt/zimbra/
Is there yet another user that needs creating?