Re: Mail Server Controversy

On Mon, 23 Dec 2002, rlambert wrote:

> I am currently trying to replace my FreeBSD mail server with a RH8 mail
> server. Is it possible to have both mail servers exist together during
> this process. I have new clients that need mail service and I want to

It is possible but I do not think you want to do it. Think about it, 
If you are using 2 mailservers which one delivers the mail to the users??
Where do the users get their mail?? Running 2 mail servers at the same 
time makes no sense unless one of them is configured to store mail and 
forward it to the primary mailserver when it comes back up. Then you 
just have a backup mailserver. It does not sound like that is what you want.

I would suggest you build the new mail server, test it, and add the users
to it. When it is time to cut over to the new server shutdown the old one,
change the dns records to point to the new one, copy the users mail from
the old server to the new one (assuming they are in the same format),
and fire up the new server. 

The mail protocol is very robust. As long as your server is not down for 
long periods of time you will not loose mail. Long periods of time is
defined as a couple of days. IIRC the rfc says 5 days actually. There are 
exceptions to what I said above most notabilly from my experience AOL
will bounce mail that doesn't get delivered within 24 Hrs. Even AOL does
not bounce for mail not delivered in a few hours though.

You should be able to plan your migration to take place in less than 
a few hours (most of the time in less than an hour depending on how 
much data needs to be moved.). Just be sure to have your DNS ttl's low 
enough so that you can do the migration and have the dns info propagate 
in a timely manner.

> know if I can have both systems running concurrently. If so, what are
> the MX records I need to enter in order to have them work. Lastly, is
> there a program that will transfer my current users from the FreeBSD box
> to my RH8 box. Thanks for your help.

You do not say how you are setting things up. Are you using sendmail, postfix,
qmail, etc. Where is your user acct information stored? where are you going
going to store user acct info on the new server (passwd file, LDAP, etc.).
Is their an imap or pop server involved?? There are many variables here.
I have never ran FreeBSD but if you are using the passwd and shadow file for 
storing user acct information and the authentication scheme for both the BSD
and linux machine is the same it might just be a matter of copying the user 
acct info to the new box. Be careful though about copying the whole file.
I am sure the system accts for BSD and Linux are different.

If the above works a simple shell script would build the home dirs., etc. for
you. Google might be able to help also. I am sure you are not the first one 
to do this.

HTH,

-- 
.............Tom	"Nothing would please me more than being able to 
[email protected]	hire ten programmers and deluge the hobby market 
			with good software." -- Bill Gates 1976

   			We are still waiting ....