Two mail servers on the same domain

[David Botham]

bind-users-bounce at isc.org wrote on 11/24/2003 03:17:50 AM:
> Dear all,
> this is a quite newbie question, I think :)
> We have an old mail server with about 200 users mail accounts.
> We want to exchange it for the new one, and we are planning to use
> following method, which we don't know if it would be correct.
> We want to install a new machine on the same domain and to configure
> mail there (postfix).
> For example a user John Thomas has an account "jthomas" on the old
> mail server. We would make a new account "johnthomas" on the new
> running mail server.
> In the DNS server we would have 
> ourdomain.sk  IN  MX 10 mailold.ourdomain.sk.
>               IN  MX 20 mailnew.ourdoamin.sk.
> So our reasoning is that in the case somebody sends an email to
> jthomas at ourdomain.sk it will go directly to maiold and when sending to
> johnthomas at ourdomain.sk it will go to the mailnew.


No.  The two mx RR you have above make all mail to any user @ourdomain.sk 
to be delivered to mailold.ourdomain.sk.  However, if mailold.ourdomain.sk 
is offline for some reason, mail would then  be delivered to 
mailnew.ourdoamin.sk.

It is worth mentioning that lack of a valid user at a mail server does not 
constitute an "offline" condition.  In other words, lack of the new email 
address on the old mail server will not signal the remote sending MTA to 
then try your backup mail server.

Try using aliases files on the old mail server to foward mail to the new 
server in during your migration.  You will have to fork lift the current 
mail files from the old server to the new server.  The finer details of 
howto migrate mail should be directed to a list more appropriate to that 
subject though.

I hope the explaination of MX RR's helped out.


Dave...


> By this method we would create all accounts in the new manner...
> Is this correct ?
> And in the case it is not, how this should be done ?
> Thank in advance for your advice
> Regards
> Dusan
>