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I was wondering if it is possible to point 2 domains to one mail server. Currently the mail server is on "" we would like to eventually move this to "".

The problem is that users already have the old server address in their email client and it will take time to change this but if we can somehow slowly move users to the new address that would be better. I'm not really sure what the best approach is for something like this.

Thanks, Aaron

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Yes you can point 2 domains to one mail server but depending of you mailserver you might have to update its configuration to handle the new domain.

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We're using a Kerio mail server. What kind of configuration would we have to update. Remember, we don't want to kill the mail server for users that have the old server listed in their email client. – Aaron Jul 1 '10 at 13:45
From what I see in the doc you have to add the new domain in Configuration → Domains but the question was "it is possible to point 2 domains to one mail server" if you want help to configure Kerio Mail server you probably want to ask a new question like "How to add a second email to Kerio mail server" – radius Jul 1 '10 at 13:51
You mean how to add a second domain to Kerio? I guess I can create a new question for that since it would be more appropriate. I just wasn't sure if had to be done on the Kerio side or the Apple OS X Server side. – Aaron Jul 1 '10 at 13:56
Yes I was meaning "How to add a second domain to Kerio" – radius Jul 1 '10 at 14:03
Are you trying to actually change the e-mail addresses, or simply move your e-mail function away from whichever server has the current A record for (maybe because it's an overloaded web server) ? – Alnitak Jul 1 '10 at 14:31

Radius just answer to you. For old server address problem you can configure a DNS record (CNAME type) that points to new MX record.

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How would Radius work? The point isn't to be changing the mail server. If we change the mail server and cause people to loose email until their address has been updated in their email then that will be a problem. – Aaron Jul 1 '10 at 13:47

You didn't specify so I will assume that you are running an SMTP server and an IMAP server/mailstore on the same machine.

Servers have hostnames not domains and are members of a zone; this is a common confusion.

If you have a machine with a hostname that accepts mail for the zone you can indeed bring up a mail server on another machine called that accepts mail for that zone.

In order to do this you should first configure the new machine to accept mail for (and probably configure it to allow your users to send outbound mail through it, preferably using a polite encrypted SMTP-AUTH setup).

Once you're happy that the new server works, you'll need to make DNS changes so that folks will use it. If you're concerned about caching, you might want to set the TTL for the zone down to an hour or even less before you start fiddling with DNS.

You should change the MX records for any zones that you want the new machine to handle to look like this:        IN MX 10

If you want to avoid reconfiguring your users' clients, you'll also want to create a CNAME that points from the old to the new:        IN CNAME

Don't forget to consider reverse DNS. What should the reverse lookup for the IP address of the new machines look like? or

Also, don't forget to modify your SPF records if you use them.

There's a lot more to migrating mail servers than this, especially if you're very sensitive to downtime and user visibility, but it's a start; hopefully you have things carefully in hand and have tested the 'restore' part of your backup process:)

Good Luck.

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