[Lula] Mail server ip changed issue.

[Peter Benjamin]

At 05:20 PM 6/28/2006, you wrote:
>Hello,
>     I wonder how to solve the mail bounce issue
>during the process of switching a mail server from one
>ip to another(same dns name). DNS changes take a while
>for the latest ip to be refreshed. So, before new ip
>information about the mail server is refreshed to
>other dns server, all the mail sent between the gap
>will be bounced. Any idea?

There are several solutions.

1) Do not worry as the email system was designed for this
type of change, and all mail will likely be delivered anyway.

You best have a good secondary DNS entry for #1 above to work.

Email is not bounced due to the temporary unavailability of
the mail server software at the resolved IP number.  It gets
a "soft" bounce, and is requeued for later delivery.  This has
already been talked about.

Email is bounced only when the DNS server states the domain name
has no IP number, that is no answer comes in, therefore the 
domain name must have been removed from the Internet, therefore
"hard" bounce the email.

Thus, having two DNS servers, a primary and secondary is key
to changing a hard bounce to a soft bounce, and getting the
mail delivered.



2) Keep mail servers at both IP numbers.  

2a) People with inboxes at the old mail server will have to 
add a second account to their email client software to access 
the old inbox.  

2b) Every day move the contents of the old inboxes to the new inboxes.



Those are the two most commonly used methods for changing the IP
number of your mail server in "small" environments.

In a robust environment, where money is available, the back up
email server was extremely useful, until the spammers started
using them directly.  This has two solutions, both not nice:

1) Copy all the filter rules from the main server to the back up server.
This is a roll your own right now, and maybe you might find some open
source that does it.  Anyone???  I have sendmail.  <g>

2) Require your end users to have AV and spam filtering on their
mail clients.


Say, is not #2 required anyway (now a days for security and reliability
reasons)?


Jeff, btw, is known as the best, lazy administrator in SoCal.
So, his opinion of no backup mail server just means he is
spending his time doing other, higher quality things with
his spare time.  Kudos to Jeff.

Until the Western Electrical Grid goes out again for several
days, and he is not getting any email, and all the mailing
lists he has subbed are getting hard bounces and unsubbing
his email address.  Or lessor mishap.  <g>  Like the cat
decides to relieve himself on his mail server, which is
also his only DNS server for his domain names.  (Is it Jeff?)

(Wow, what a good day it is today!  Sun is out, fresh air
coming in.  Quite a change from the last 5 days.) 

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