Re: [exim] Building virtual domain on multiple mail server

Stephen Liu wrote:
> Hi folks,
>
>
> This is my first posting on this mailing list. I never ran Exim as MTA
> before which is completely new to me.
>
>
> What I'm exploring is as follow;
>
>
> - building multiple mail servers on guests of a Xen box running Debian
> Etch (I can make it without problem)
>
>
> - all mail servers running Exim as MTA (I hope I can make it. After
> finish I'll clone its image creating multiple mail severs on the Xen
> box. I did the later without problem before running other MTA). Each
> guest being a mail server has its own servername/hostname and local IP.
>
>
> - the most important goal is how to run multiple domains on one
> external IP. Each incoming mail can be delivered to its own mail
> server. It is similar to virtual domain. I made it on one mail server
> before running other MTA. But I have no idea how to build virtual
> domain on multiple mail servers.
>
>
> Could you please shed me some light? Pointer would be appreciated.
>
>
> Regarding DNS server, bind9, do I need building it on each mail server?
> Can I build only DNS on one mail server to be shared by others?
>
>
> TIA
>
>
> A side question. Registration to Exim-user forum has been disabled by
> the site maintainer. Is there any way to register? Thanks.
>
>
> B.R.
> Stephen L

This message came via the exim-users Mailing list, so it would appear
that you have all the registration you need.

As to the above complex 'plan', one presumes your goal is to offer a
'package' to each of many customers.

AFAICS, the Xen guest approach will need a unique *external* IP for each
guest - though any such guest may then run many <domain>.<tld> on that
one IP.

IF all you can spare is ONE external IP, then you'll want to put all
customers on the same instance of Exim, which will keep them separate -
not by IP, but by <domain>.<tld> - *including* allowing for separate
filter rules as well as users communities. Each 'customer' can then
admin their 'partition' via access to anything from flat-files to an SQL
DB. Exim supports just about anything it can be allowed to read.

Properly set up, there will not even be a need to restart Exim after
changes, as it can read-in external files/DB's each time a new child
process is spawned - which happens for every new connection, in or out.


DNS:

DNS *may* be run (also) on an MTA - but *should* be run on two or more
OTHER boxes, and not all on the same backbone.

You will need AT LEAST your PTR RR in the IP-block holder's DNS (your
data center / colocation provider or broadband upstream).

They can also hold your MX and other DNS entries if their fees and
response time to change orders are suitable, saving you the hassle of
running a pair/trio of DNS services.

HTH,

Bill Hacker