I got a setup of 3 nodes (ldap,mta,mailbox) and I can't send system mails on mailbox node.

I've tried to follow wiki details as explained here: How to "fix" system's sendmail to use that of zimbra - Zimbra :: Wiki

but there's no sendmail in /opt/zimbra/postfix/sbin/sendmail so I'm not sure about the safest way to install a compatible binary without interfiring with zimbra.

I would like to do that on mailbox and ldap nodes.

any ideas?