political mail issues

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chriske911

I have a problem where I have 2 sites on both european and american
continent
each site has an exchange server

offcourse being just one AD domain there is always one mail server
possible as highest priority mx record

creating subdomains would be the answer for both sites to have a
default high priority XC server

management doesn't want a subdomain suffix in the email adresses

is there a way to redirect mailboxes to the correct subdomain with the
help of DNS records?

or anther way that customers only need to use (e-mail address removed)
instead of (e-mail address removed)?

thnx
 
Yes, there is another way called a smart host.
However, that may not meet all of your needs. Consider a company such as,
oh, Microsoft. They have one domain name microsoft.com. Several equally
costed MX records.
microsoft.com MX preference = 10, mail exchanger = mailb.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mailc.microsoft.com
microsoft.com MX preference = 10, mail exchanger = maila.microsoft.com

Do all of those have to be in the same location? Or country? Or continent?
Nope. But, and this is a big consideration, once one of those mailers has
the message, it must be able to 'deliver or die'. What I mean by that is
that if it accepts the message, by SMTP rules it now must deliver it to the
next host. That next host could be local (geographically speaking) or it
could be around the world. The next host could be another SMTP mailer or it
could be the users mail store.

I'm going to make an assumption that once on your network, you don't want to
burn up the WAN link between Europe and America.

So to make this work the way you are describing, I would personally prefer a
smart host vs. an Exchange server, deployed in Europe and America. Both
smarthosts would know the location and have routes to the final destination
servers. That route could be a subdomain (that you register with external
DNS. I.E. us.company.com and europeancountry.company.com). To make this
work, the smarthost would have to know the information required for routing.
If it gets a piece of mail for (e-mail address removed) it would look that up in
it's directory, rewrite the delivery address, and then deliver it to the
appropriate mailer via the internet. That would look like
(e-mail address removed) -->change to (e-mail address removed) and then send it to
the appropriate mailer.

That's valid if you don't want the traffic to route over your wan keeping in
mind that all users send as (e-mail address removed) regardless of location.

Using DNS alone wouldn't do this because DNS doesn't have enough information
to route your mail appropriately.

If you need more details, feel free to contact offline.

Al
 
In
chriske911 said:
I have a problem where I have 2 sites on both european and american
continent
each site has an exchange server

offcourse being just one AD domain there is always one mail server
possible as highest priority mx record

creating subdomains would be the answer for both sites to have a
default high priority XC server

management doesn't want a subdomain suffix in the email adresses

is there a way to redirect mailboxes to the correct subdomain with the
help of DNS records?

or anther way that customers only need to use (e-mail address removed)
instead of (e-mail address removed)?
Click to expand...

Not with DNS records.
Exchange will send mail for unresolved recipients to another mail server(the
other Exchange server in this case) but this can pose a problem for
recipients that don't exist on either server, so it will loop between the
two servers I think something like four or five times and will increase
network activity between the servers. But, it is easy to set up, on the SMTP
virtual server properties, Messages tab "Forward all mail with unresolved
recipients to host:" with the other Exchange server name. Then you can use
the (e-mail address removed) format with MX records with equal prioity.


I agree with Al, a Smart Host would be great, and could direct the mail to
the correct mail server. The drawback to a smart host is, it requires extra
administration because the email address will have to be configured in the
smart host in addition to the Exchange server.
 
Al Mulnick wrote on 13/05/2005 :
Yes, there is another way called a smart host.
However, that may not meet all of your needs. Consider a company such as,
oh, Microsoft. They have one domain name microsoft.com. Several equally
costed MX records.
microsoft.com MX preference = 10, mail exchanger = mailb.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mailc.microsoft.com
microsoft.com MX preference = 10, mail exchanger = maila.microsoft.com

Do all of those have to be in the same location? Or country? Or continent?
Nope. But, and this is a big consideration, once one of those mailers has
the message, it must be able to 'deliver or die'. What I mean by that is
that if it accepts the message, by SMTP rules it now must deliver it to the
next host. That next host could be local (geographically speaking) or it
could be around the world. The next host could be another SMTP mailer or it
could be the users mail store.

I'm going to make an assumption that once on your network, you don't want to
burn up the WAN link between Europe and America.

So to make this work the way you are describing, I would personally prefer a
smart host vs. an Exchange server, deployed in Europe and America. Both
smarthosts would know the location and have routes to the final destination
servers. That route could be a subdomain (that you register with external
DNS. I.E. us.company.com and europeancountry.company.com). To make this
work, the smarthost would have to know the information required for routing.
If it gets a piece of mail for (e-mail address removed) it would look that up in
it's directory, rewrite the delivery address, and then deliver it to the
appropriate mailer via the internet. That would look like
(e-mail address removed) -->change to (e-mail address removed) and then send it to
the appropriate mailer.

That's valid if you don't want the traffic to route over your wan keeping in
mind that all users send as (e-mail address removed) regardless of location.

Using DNS alone wouldn't do this because DNS doesn't have enough information
to route your mail appropriately.

If you need more details, feel free to contact offline.

Al
Click to expand...

that's what I came up with too
a sort of mail front server for routing to the correct back end servers
hosting just one of those at an ISP somewhere in te world would do it
for us
there are only about 250 employees worldwide

but I thought of a kind of redirection using DNS mailbox records or
something like that
off course it would make things more complicated
since every change would have to be followed by a manual or half
automatic DNS update

but indeed, the external mail routing is taking up a lot of bandwidth
of our WAN link
I don't really care if it's internal mail cause that's the way it has
to work
but for mail coming from outside it could be avoided
simply by implementing sub domains but that's not flying with
management

and offcourse they are right by saying it would complicate matters for
our customers
that's why the elaborate setup for something so simple

what exactly do you mean by smart host?
a mail server of any kind wich does relaying or something else
entirely?

thnx
 
A smarthost is a mail routing host that is smart enough to know mail stores
and routes and can match up mail with the stores via the appropriate route.
It's often deployed in situations very similar to this one where I need to
accept mail for one domain and properly rewrite the destination and send it
along the most appropriate route to it's final mail store.

Using DNS records would be cumbersome and is not often used. Not sure how
many mailers would even look at those records to be honest and it would
likely break up some of the efficiencies of the sending host.

Downside to smarthosts are that you have extra hops in the path and extra
hardware as well as some sort of method to update those smarthosts.

FWIW, your wan link doesn't need to be taken up with email. You could route
all of your email via Internet if you wanted. Might make a smart host
uneccessary as well, but you'd have to check into that and decide. I'd
likely want to use some sort of transport encryption if I went that route
(TLS?)


Just a thought,

Al
 
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