Moving Mail Server to another location / IP address?

[Christopher Weldon]

On Feb 8, 2007, at 7:40 PM, Ashley Aitken wrote:

>
> Howdy All,
>
> I need to move a machine running MacOSX Server 10.4.8, particularly  
> mail services but also some Web sites to another location and IP  
> address.
>
> My understanding is that Internet mail uses a store-and-forward  
> model that attempts for 4 hours (or so) to deliver an email.  So I  
> am hoping I have four hours to move the machine.

Umm, 4 hours is incorrect. Due to the way DNS records propagate  
through the internet, it can take up to 48 hours or so before a  
server will flush its cache and start looking for new DNS records.  
Granted most of the time it's significantly less than that, but it's  
dependent on how everyone else has their DNS servers setup as well as  
what TTL periods you have set in your DNS entries.

>
> I guess I have to:
>
> 1.  Change the IP address of the machine
> 2.  Change the DNS MX record for the mail server
>

Don't forget to update the hostname entry in DNS with your new IP  
address!

> and, of course, physically move the machine (at which time I might  
> also add a new larger drive to the machine and copy the original  
> drive onto it with Disk Utility).
>
> I believe there is a process and command for changing the IP  
> address of a MacOSX Server installation.  Will that be adequate?

If you are running your DNS on the OSX server, I'm not certain. I'm  
100% certain that if you have your DNS hosted elsewhere, then it  
won't be sufficient for DNS.

>
> I don't have a second email server (that is recommended, I believe,  
> for such situations).  I realise people won't be able to access  
> their email during the outage but will we lose any email sent to us?

You won't lose any emails as long as the sender's mail relay  
appropriately follows SMTP rules. Messages are generally timed out  
for up to 72 hours before returned to the original sender. During the  
4 hour downtime, the relay will simply hold onto the message until it  
can actually reach the email server. I think the biggest thing you'll  
lose is SPAM (and we all know how much we love our SPAM).

>
> Further, is there a particular order I should do all this:
>
> 1.  Take machine off network at old location
> 2.  Change the DNS MX record to the new IP address (allowing time  
> for caches to timeout)
> 3.  Copy OS & data on old drive to new drive
> 4.  Boot (off network) and change IP address on OS on new drive
> 5.  Put machine back on network at new location.

Because you don't have any redundancy in your setup, this order seems  
fine.

>
> This is not a critical email server used by important people, but  
> it is our family and small business email server, so I don't want  
> to stuff things up.
>
> Finally, I would normally do a backup of the server before doing  
> such a change.  I believe copying the old drive to a new drive is  
> doing that (i.e. I could go back to the previous situation quite  
> easily).
>
> Thanks for any suggestions, corrections, experience.
>
> Cheers,
> Ashley.
--
Christopher Weldon
President & CEO
Cerberus Interactive, Inc.
cweldon at cerberusonline.com
(866) 813-4603 x605