Zimbra Open Source as Secondary MX

[dfriestedt]

I use Zimbra NE as our primary email server and everything works fine. I'm trying to setup Zimbra Open Source as a secondary MX that holds and sends mail to my primary mail server when it goes down.

email domain = example.com
Zimbra NE = mail.example.com
Zimbra Open = mail2.example.com

DNS for example.com
MX10 = mail.example.com
MX20 = mail2.example.com

Under the admin panel of mail2.example.com I set "Relay MTA for external delivery" to mail.example.com. I also created a domain example.com under mail2.example.com.

when I close port 25 on mail.example.com (forcing mail to mail2.example.com) I get the following message when I send email to example.com


This is the mail system at host mail.sendingdomain.net.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<dfriestedt@example.com>: host
mail2.example.com[xx.xx.xx.xx] said: 550 5.1.1
<dfriestedt@example.com>: Recipient address rejected:
example.com (in reply to RCPT TO command)


????

[LMStone]

Originally Posted by dfriestedt

I use Zimbra NE as our primary email server and everything works fine. I'm trying to setup Zimbra Open Source as a secondary MX that holds and sends mail to my primary mail server when it goes down.

email domain = example.com
Zimbra NE = mail.example.com
Zimbra Open = mail2.example.com

DNS for example.com
MX10 = mail.example.com
MX20 = mail2.example.com

Under the admin panel of mail2.example.com I set "Relay MTA for external delivery" to mail.example.com. I also created a domain example.com under mail2.example.com.

when I close port 25 on mail.example.com (forcing mail to mail2.example.com) I get the following message when I send email to example.com


This is the mail system at host mail.sendingdomain.net.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<dfriestedt@example.com>: host
mail2.example.com[xx.xx.xx.xx] said: 550 5.1.1
<dfriestedt@example.com>: Recipient address rejected:
example.com (in reply to RCPT TO command)


????

A while back we looked at this solution and found it unsatisfactory for a number of reasons.

If you want your backup MX on the same subnet as your NE servers, you can just add another NE server and set it up as an MTA-only (plus LDAP-replica) host.

If you want your backup MX in another data center far away from your production Zimbra farms, we have found it easier to just set up a plain vanilla Postfix box. Both the Postfix docs and the No Starch Press book The Book of Postfix have easy-to-follow instructions for setting up a backup MX and properly dealing with potential backscatter issues.

The trick is to get the valid email addresses out of Zimbra (there is a good wiki article on this with a dynamite script) including aliases, distribution lists, resources, etc. Then you'll need to write some additional scripts: one on the Zimbra server to automate the running of the first script, and one on the backup MX to import the list of valid email addresses and zimbra domains, and update the Postfix config on the backup MX accordingly.

That script work is pretty straightforward, but if you need help, just say so.

All the best,
Mark