How to send mail to an external domain with the same name as the internal domain.

[glang]

Hi all,

I've been messing with this one for days and was hoping someone can provide some incite. I have an internal Zimbra server running on the "domainname.com" domain. It is working perfectly and can send/receive email to/from anywhere without problems unless I try to send to the external "domainname.com" domain. For a more in-depth explanation:

I'm running split DNS for the "domainname.com" domain.
The server is "bluewhale.domainname.com" and the Zimbra domain is "corp.domainname.com". If I want to send to an internal user I send a mail to "username@corp.domainname.com" and everything works fine. But, if I try to send to an external user at "username@domainname.com" I receive a message saying ": mail for domainname.com loops back to myself".

Any ideas?

[SynUK]

I have had this working quite well. I don't have the exact documentation with me at the moment but have a look at :

Split Domain - Zimbra :: Wiki

If that doesn't work, I will dif out the instructions that I used to do it.

[glang]

I've looked over what you provided but, though the problem is similar, is not exactly what I'm dealing with.

I have an external server hosted by Network Solutions on the "example.com" domain that we send mail to by addressing it to "userid@example.com". I also have a Zimbra server on the "example.com" domain--running it's own DNS--that we send mail to be addressing it to "userid@corp.exmaple.com". Each user can have an account on both mail systems and needs the ability to receive mail from both. Both servers work fine and we can send from "example.com" to "corp.example.com" with no problem. We just can't send from "corp.example.com" to "example.com". The systems are not secondary and primary, but two completely separate servers handling two sets of mail.

It's my understanding that the Zimbra server, being a part of the "example.com" domain believes that anything sent to "userid@example.com" is going to itself so it doesn't send it but I'm not sure if that's the case or, if it is, how to work around it.

[glang]

Well, I don't know if I did it the correct way but it appears to be working.

What I did was placed the IP address for the MX record of the external server into my /etc/hosts table, pointing to "example.com". I then turned off "enable DNS lookups" in the Zimbra management suite.

To test I sent an email (using Zimbra) from "userid1@corp.example.com" to "userid1@example.com" and it transferred successfully. I then reversed the process and sent an email (using Network Solutions) from "userid1@example.com" to "userid1@corp.example.com" and it also worked.

Does anyone see a problem with the changes I made that may negatively impact other areas I didn't consider?

[veronica]

You have made a correct setup. It was just a matter of setting up MX properly