[trev.h]

We have all our eggs in one basket, an MS Win200k mail server that is notoriously unreliable.

I don't want to jump straight to a Linux replacement yet, I like the idea of spreading the load and having a Linux mail serving running in parallel. If one fails, the other will always be working, thereby doing a back to back analysis or performance and reliability.

In short, can it be done?

Thanks
Trev.

[ed209]

It can be done but you are going to have to put on your patience hat and your reading glasses. Here is what I think you want to do correct me if I am way off:

You want a backup mail server protecting you from losing messages when the flakey win2k exchange box goes down like it always does on friday afternoon?

or

You want a real time Highly Available mail server system with failover to the secondary server when the master is unreachable?

The first scenario is definately do able. You just need some hardware and a couple cd's of your favorite *nix distro. My current favorite is knoppix because it is based on debian which IMHO is the best thing since Canada considered changing its pot laws ... but I disgress

If it was my job to do I would choose the following:

fast pc hardware ( possibly with on board raid controller but that can be a hassle )
knoppix ( linux distro )
postfix ( main mail server provides pop3 and smtp )
courier-imap ( this is your imap server )
squirrelmail+apache ( handy webmail service will add some flare to your mail system and make your users think you are the greatest )
mailman ( handy mail list manager not necessary but handy when you see the better performance of your linux box and then turf the old system and need to setup new mail lists in a straight forward manner )
SpamAssasin ( spam filter == sweet!! )

First things first you will need to install your machine get it stable, no spastic crashes or lockups when you access the disk or move the mouse ( that happens with shared interrupts BTW ).

Next you have the arduous task of installing,configuring,verifying, postfix. This can be painless or painful depending on how much you like reading. Here are some tutorials:

Redhat Postfix Howto:
http://www.redhat.com/support/resour...WTO/book1.html

Mailman Postfix Howto:
http://mail.python.org/pipermail/mai...er/022370.html

Migration howto Exchange to Postfix:
http://www.unixwiz.net/techtips/post...nge-users.html

Postfix Homepage:
http://www.postfix.org/

Courier-Imap Homepage:
http://www.inter7.com/courierimap.html

Postfix + CourierImap+LDAP howto:
http://annapolislinux.org/docs/plc/p...rier-howto.txt

Here is a basic outline of what you need to do:

Setup postfix to be a mail gateway, accepting all mail for your domain and forwarding it all to the exchange server. This is handy because you can do spam filtering on the server side with Spamassasin and cut down on the mail that ends up on your exchange box.

The clients still connect to the exchange server to get their messages but if the win2k box rolls over and dies on you all your messages just queue up on the postfix box. Then if it is going to take too long to get the win2k box going again you can change DNS to point to old mail server to the new mail server. Of course you would need all the old stored messages to be on both machines and that will require a little scripting.

If you are trying for the second option, depending on cash available to you, you can take a look at Steeleye softwares Lifekeeper product. It is high availability software for enterprise applications, may be worth buying.

I hope that helps,

ed

[trev.h]

Sounds good.
I like option one because it will be a bit cheaper, but I need to think about automating things.

In the unlikely event the Linux server fails, the windows server needs to change. I could use a script running something like a ping from win to linux and when the ping fails for a given number of events, the config on windows changes.

In the likely event the windows server fails, I could have a similar process on the linux server, but need some action to take. Maybe a mail or broadcast to tell users to switch to another client mail config, but what would be really good would be something to automatically initiate a client change.

Most of this could be done with Windows and Linux scripts and would be an interesting project.

Thanks for the info ed209.
Trev.

[soup4you2]

Here's my suggestions..

I wrote up a easy to follow howto on making a mailserver.. which supports

Postfix + Procmail + Spamassasin + Amavis Virus Scanning

And if you want webmail Squirrelmail or horde are the best in my opinion..

here's a link to my guide..
http://screamingelectron.org/phpBB2/viewtopic.php?t=774

then you could always use a round-robbin or something to distribute the load or take over if 1 should fail.