domain coexistence

marcmac · Post by **marcmac** » Sat Feb 04, 2006 11:07 am

Not sure if this got posted or not:
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Split Domain Setup

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We are often asked how to configure Zimbra Collaboration Suite so that

some accounts are moved/migrated to Zimbra but other accounts continue

to live on existing mail system. This is possible IF your mail system

offers some of the mail routing features that the Zimbra offers.
Consider this example:
- Your domain is example.com.
- Your existing mail infrastructure lives on the host

"mail.example.com" (assuming single node install for simplicity -

what we are discussing should also work on multi-node).
- Your domain example.com has MX records that to point to host

"mail.example.com".
- Users "foo@example.com" and "bar@example.com" existed in the old

system.
- You have installed Zimbra on the host "zimbra.example.com" and

created the domain "example.com" on it also.
- You have migrated the mailbox of the user "foo@example.com" to

the Zimbra system, using one of our migration tools documented

elsewhere.
Some issues to consider as a result of such splitting your domain:
- The end user "bar@example.com", who is not being migrated, will

be unaware of the change insofar as regular email is concerned.

Global address list (GAL) experience should also not change for

this user. There maybe some issues around group calendaring

between the two systems (assuming your existing infrastructure

supports group calendaring); we are working on these issues.
- The end user "foo@example.com" will need to be educated and

user's desktop software might need some minor configuration

changes. For user uses IMAP, s/he must be told to change IMAP

server setting to where Zimbra is installed. If s/he uses

Outlook/MAPI, Zimbra MAPI plugin should be deployed. If using

webmail, the address of the new Zimbra Web Client address needs

to be communicated to the user.
- If "foo@example.com" is using a mail client that has outgoing

SMTP configured with SMTP AUTH enabled, and SMTP AUTH

functionality is required by your network topology or roaming

users, then based on where authentication information lives (a

decision you will make below), user may foo@example.com or may

not require changing their outgoing SMTP setting.
- You will have to pick either the Zimbra system or your existing

system to be the "authoritative" system for your domain. Let's

call the authoritative system the master, and the other one the

slave. The master MTA must be aware of all accounts on the

domain, and must reject on RCPT TO: those accounts that do not

exist in either system. The slave MTA must accept mail for

accounts hosted in the slave system, and must forward mail for

all other accounts on the domain to the master MTA.
- Note that because of the above master/slave mail routing

requirement, you will have to perform some type of provisioniong

step on both the slave and the master for an account that lives

on the slave system.
- For ease of administration you should keep any GAL on only one of

these systems - avoids duplication. However this requires one

these systems be able to proxy to the other for GAL (Zimbra can

use a non-Zimbra LDAP server). If proxy is not possible some

sync method needs to be written.
- Zimbra is also able to authenticate users on a remote LDAP

server, in case you have a portal or user page backed by LDAP

where passwords are changed. Note that, out of the box, Zimbra

user's password will live in the Zimbra system. If passwords

live remotely, it is possible the old system can continue to SMTP

authenticate users who live on the Zimbra system. If that is the

case, then a Zimbra user with SMTP AUTH can continue to use the

old system's MTA as their MTA, assuming it is visible on the

network.
Please read the following discussion of how to provision and configure

Zimbra as either a master or as a slave.
If you decide to use Zimbra as the master system, then you should also

carefully read the section on how Zimbra is configured as the slave -

this will show you what functionality is required of your existing

mail system so it can be a slave. Vice versa if you are going to use

Zimbra as the slave system.
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Configuring Zimbra as the Master

--------------------------------
Create corresponding accounts on the Zimbra system for all the

accounts that will live on the slave system. Note that

bar@example.com is not migrating, and lives on the slave.
$ zmprov ca bar@example.com
Configure mail routing for this account so email flows to the slave

system for this account:
$ zmprov ma bar@example.com zimbraMailTransport smtp:mail.example.com
Note that we are not using any catch all (akin to "luser_relay")

tricks here. Master needs to be authoritative, and if it forwards

unknown accounts, then we would have a mail loop.
(Note to Zimbra: TBD: do we need to set any other attributes to make

this forwarding account on the Zimbra side more of a dummy? Instead

of random password, it would better to have login disabled, but

zimbraMailStatus still has to read enabled.)
Change your MX record so mail from the cloud flows into the Zimbra MTA

first. (This is the last step! You will bounce mail if you make this

change before configuring the entire system and testing that mail flow

is working as desired.)
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Configuring Zimbra as the Slave

-------------------------------
The slave system needs to accept mail for accounts that live on the

slave, but must forward all other mail for accounts on this domain to

the master.
You can accomplish this piece of mail routing by saying:
$ zmprov md example.com zimbraMailCatchAllAddress @zimbra.com

$ zmprov md example.com zimbraMailCatchAllForwardingAddress @zimbra.com

$ zmprov md example.com zimbraMailTransport smtp:mail.example.com
The first two commands (in combination) tell Zimbra postfix to accept

all addresses in the @zimbra.com domain as valid addresses.
The third command establishes default mail routing for the domain.
We also highly recommend that, in a slave Zimbra system, you turn off

DNS lookups and internet wide message routing from the slave host and

route all mail through the master. You can accomplish this by:
$ zmprov mcf zimbraMtaRelayHost mail.example.com

$ zmprov mcf zimbraMtaDnsLookupsEnabled FALSE
Make sure to configure mail.example.com to accept mail relayed by

zimbra.example.com.
All these commands require that after running the whole set of them,

you do:
$ postfix stop

$ postfix start
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Examples of Mail Flow

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- Zimbra is master, mail sent from the internet, account lives on

slave.
internet ->

zimbra.example.com postfix server ->

account transport says to use smtp:mail.example.com ->

mail.example.com existing infrastructure MTA ->

mail.example.com existing infrastructure mail store
- Zimbra is slave and mail sent from foo@example.com (zimbra) ->

bar@example.com (old system). Assume foo is using Zimbra AJAX

client.
foo's web browser ->

zimbra.example.com tomcat server ->

zimbra.example.com postfix server ->

account not local, finds domain transport setting ->

mail.example.com existing infrastructure MTA ->

mail.example.com existing infrastructure mail store

aaronrryan · Post by **aaronrryan** » Tue Feb 07, 2006 2:19 pm

When I try to change the zimbraMailTransport variable, I get the following error:
$ zmprov md example.com zimbraMailTransport smtp:mail.example.com

ERROR: service.INVALID_REQUEST (invalid request: zimbramailtransport is immutable)

Is there an alternative method of changing this, or is there a force flag?
Thanks,

14319KevinH · Post by **14319KevinH** » Tue Feb 07, 2006 2:40 pm

You'll need to be using the latest GA release to make this change. Sorry we didn't mention that is the first post.

roastpork · Post by **roastpork** » Fri Feb 10, 2006 9:15 am

In the above (marcmac) example, what is zimbra.com? I thought we were dealing with example.com as our domain.
Edit: OK, got it, an alias.
If we are just talking about the example.com domain the only entry we would need to forward accounts not found on zimbra.example.com for example.com to another mail server is the third line:
zmprov md example.com zimbraMailTransport smtp:mail.example.com
And this will first attempt delivery localy.
Thanks.

marcmac · Post by **marcmac** » Fri Feb 10, 2006 9:51 am

[quote user="roastpork"]In the above (marcmac) example, what is zimbra.com? I thought we were dealing with example.com as our domain.
Edit: OK, got it, an alias.
If we are just talking about the example.com domain the only entry we would need to forward accounts not found on zimbra.example.com for example.com to another mail server is the third line:
zmprov md example.com zimbraMailTransport smtp:mail.example.com
And this will first attempt delivery localy.
Thanks.[/QUOTE]
My mistake - should read example.com

dillera · Post by **dillera** » Sun Feb 26, 2006 1:57 pm

Please edit the message- its way too confusing... can't you just edit it and get rid of zimbra.com?

phoenix · Post by **phoenix** » Sun Feb 26, 2006 2:14 pm

[quote user="dillera"]Please edit the message- its way too confusing... can't you just edit it and get rid of zimbra.com?[/QUOTE]

It's not that difficult to read but you could always put it on the wiki and save marcmac a bit of work, I think he does plenty of support here.

marcmac · Post by **marcmac** » Sun Feb 26, 2006 4:44 pm

Actually, I already put it there:

So">http://wiki.zimbra.com/index.php?title=Split_Domain
So if you want to make changes, go for it.

dillera · Post by **dillera** » Mon Feb 27, 2006 6:47 pm

Ok, if things are going to the wiki, that makes sense. I would imagine that this sticky gets a lot more traffic than the wiki page however.

mintra · Post by **mintra** » Mon Mar 27, 2006 5:53 pm

OK I admin I dont understand this (I will re-read the wiki version when I am less tired).
If I want to do things this way. Two Zimbra servers. Both with the same domain

both with separate mx records on higher priority than the other.
Main will normally go to mx1.mydomain.com but if this is busy or down it will go to mx2.mydomain.com.
Ideally I would like it if any mail gets into mx2.mydomain.com it would forward it to mx1.mydomain.com
However if mx1 fails completely (HD failure etc) a copy of all the mail is avaible on mx2.mydomain.com, in separate imap mailboxes.
This could be done with imapsync or similar.
So all I would need to do is set up the same accounts on each server.
The problem is that the mail getting to mx2 could not be forwarded to mx1 as they are both on the same domain mydomain.com
If I could forward fred@mydomain.com to fred@213.160.23.123 where the IP address was the address of my primary server mx1 this would be OK.
Another suggestion I have seen is to set up another domain on the primary mail server so that the mail to fred@mydomain.com thet gets to mx2 is forwarded to fred@mx1.mydomain.com.
This would then have to go to fred@mydomain.com in the primary server.

a copy could be sent to the local server.
Is this all silly?