I'm not sure what I'm doing. Exchange has been working a long time. I just installed a mac mail server postfix/dovecot. They both work but not together.

If I send email directly to the new server with myemail@mynewmacserver.com, I can send email to the Internet and I can receive email at the myemail@mynewmacserver.com.

But, if I log onto my exchange account with OWA and I put in myemail@mynewmacserver.com I never receive it and I never get any errors back in OWA or on my mac server logs. It just disappears.

On the mac, I thought that as long as I had mail running and had SMTP set to allow incoming email checked it would receive email from anywhere. How can I make my Exchange server send email to the mac box if the email doesn't exist in the exchange server? Is this where I would put a new SMTP connector and a bridgehead using DNS?

Thank you for any help.


If I'm reading your requirement correctly, issue of coexistence of Linux/Exchange mail servers is in the design limitations of Exchange. You will need to treat your Postfix box as a smarthost and ensure your company's MX records reflect that as the front end server.

On Exchange, configure the IMC to deliver all mail to this Smart Host.

Review MSKB# 265293

In order to maintain continuity with your domainname, you'll need to ensure Postfix modifies the email address in order to reflect a consistent email domain name.

See the following on hosting Virtual Domains when configuring Postfix:


Once complete, you can still logon to OWA and retrieve messages as desired.

Last point to consider is to ensure neither server is configured properly so it's not flagged as an open relay.

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This could be tricky. Is the new domain name, 'mynewmacserver.com' from your post, set up in the public DNS and have a proper MX record that points to your Mac server? I'll assume it is and that you can send e-mail in from the outside without error.

If both of these mail servers are behind a NAT router, the Exchange Server may be trying to resolve the IP for your MX record and seeing the external IP address, in which case your router may not know what to do with that traffic, and it's simply not able to connect.

If that is the case you'll need to put an entry in your hosts file on Windows to ensure the host specified in the MX record for the domain resolves to the internal IP address of the Max server on your network. Then it would be trying to connect to the internal IP which would be direct and not get the router involved.

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Tricky indeed - especially with the little information.

Are both servers on different domains (e.g. myexchangeserver.com and mynewmacserver.com)? If yes, are both domains properly setup on internal and/or public DNS (MX Records, PTR)? Does each Server have it's own public IP or do they share one?

First, I would check if you can SMTP into both servers (telnet host.myexchangeserver.com 25 and telnet host.mynewmacserver.com 25 - of course using the real FQDN for both servers)

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