Configure Zimbra to use external relay for specific domains

[emram]

Hi,
I am running Zimbra 5.0.18 GA 3011 on an Ubuntu server with an internal IP address. I have a split brained dns server installed on the server.

When our users send an email to a particular domain say example.com, our server gives them the message that the mailserver.example.com said 554 Transaction
Failed Spam Message not queued. (in reply to end of DATA command)
I've contacted the postmaster@example.com and he said that the message was released. However, we continually get this bounced mail when we send mail to example.com.

So, now what I want to do is to use an external smarthost to relay mail only for example.com. I want some guidance on how to configure zimbra to relay mail for example.com to the smart host. The smart host requires authentication.

I was also thinking of placing an A record (or do I need a MX record) for mail.example.com giving it the IP address of the smarthost in our splitbrained internal dns server. I think doing this will tell my zimbra server to connect to the smarthost for mail addressed to example.com. With this set up, will the smarthost forward the email to example.com or reject the mail because of unknown user.

Further, I tried to telnet to mail.example.com on port 25 from the zimbra server and it permitted it to relay mail only for users in the domain example.com.

I am a newbie with Zimbra and is more knowledgeable with Lotus Notes where I can add relays for particular domains by just modifying smtp server documents.

Appreciate your help.

Thanks,

emram

[phoenix]

How about this: Transport Table for external servers - Zimbra :: Wiki

[emram]

Originally Posted by phoenix

How about this: Transport Table for external servers - Zimbra :: Wiki

Thanks for your reply. How about setting up the smarthost authentication?

[emram]

This is correction to my initial post. In my initial post, I mentioned that I can telnet to the mail server of example.com and that I can relay mail to users in example.com.

After entering data on the telnet session, I got the 554 message as shown below:

554 Transaction Failed Spam Message not queued.
Connection closed by foreign host.

[phoenix]

Originally Posted by emram

Thanks for your reply. How about setting up the smarthost authentication?

If you mean outbound SMTP authentication the search the wiki for the word 'authentication'.

[emram]

Originally Posted by phoenix

How about this: Transport Table for external servers - Zimbra :: Wiki

I read that wiki and was considering it and then I read Outgoing SMTP Authentication - Zimbra :: Wiki .
In the latter wiki, it talks about setting a relay host to route all mail.

What I want is to route only for the particular domain to the external smart host which was shown in the first wiki.

So, should I just follow the first wiki and then skipp the setting a relay host and go straight to enabling smtp authentication?