I have followed the multi-server installation instruction.

MX record point to 10.6.1.27
Zimbra LDAP and Mail store installed on 10.6.1.26 and MTA installed on 10.6.1.27

/etc/hosts is configured as follows on both the machine

127.0.0.1 localhost.localdomain localhost
10.6.1.2x hostname.domain hostname

/etc/resolv.conf point to my local network DNS.

Now I am trying to send email out and the email is deferred. In the status I find that the origin IP is 127.0.0.1 origin host is localhost.localdomain and the error from the recipient domain mta says "550: your access to this mail system is rejected due to sending mts's poor reputation."

How do I fix this error.