We are deploying Zimbra in a test environment for evaluation purposes. We have an exchange 2010 server we want to be the primary server.

The exchange server receives messages from the zimbra server. However, the exchange server does not send email to the Zimbra server. The queue lists 'local loop detected.'

I have configured a send connector to send email to zimbra-server.mydomain.com to the zimbra server's IP address as a relay host and it has a cost of 1.

Exchange Configuration:

1. Send and Receive connectors for Zimbra server.
2. For the user hosted on the Zimbra server, I created a mail user and associated with the Active Directory account as follows:
a. Enable-MailUser -Identity 'user@mydomain.com' -Alias 'user' -ExternalEmailAddress 'SMTP:user@zimbra-server.mydomain.com' -PrimarySMTPAddress 'user@mydomain.com'

Zimbra Configuration

Run commands from CLI:
1. $ zmprov md mydomain.com zimbraMailCatchAllAddress @mydomain.com
2. $ zmprov md mydomain.com zimbraMailCatchAllForwardingAddress @mydomain.com
3. $ zmprov md mydomain.com zimbraMailTransport smtp:test-exchange.mydomain.com:25
4. $ zmprov mcf zimbraMtaRelayHost test-exchange.mydomain.com:25
5. $ zmprov mcf zimbraMtaDnsLookupsEnabled FALSE

I am not sure where this is failing on the exchange server. Any ideas?