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Exch 2000 with different local dns name

By sach_shin2001 ·
Dear Friends,
I need urgent help,
I have local domain name abc.com. But I have registered domain name abcd.com.
Now I want to load exchange server on my local server.Uptill now,users in my domain were connecting to some ISP exchnage server using POP account through wingate.But now I want ot set up exchange server.I want to keep local domain name as it is, but still want to use abcd.com for external email forwarding.Is it possible?what kind of dns settings are required to be done on the isp dns server?

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by ChrisDent In reply to Exch 2000 with different ...

Just a couple of questions first to clear up the assumptions I made while writing this.

abc.com is a local domain with no public records (internal only)?

abcd.com is the public domain with a record elsewhere (external domain)?

Does all incoming e-mail for the domain abcd.com want to be recieved by the exchange server?

Do all internal users need to be able to send out of their e-mail address on the abcd.com domain?

Okay, these are with those above I also assumed that abc.com is the name of your Active Directory DNS as well.

To set this up, in my opinion the best way would be:

Exchange Server:

On the Exchange Server add an SMTP address for each mailbox as <username>@abcd.com. This should be the default (reply) address.

E-mail addressing for abc.com is unnecessary unless I misunderstand how your domain is set up.

If abc.com is also an external address you wish to recieve on then add that to the list of addresses on each account so the users can recieve on it. The address it sends as is determined by the default address for each user.

The Exchange server also needs to be publically available on port 25 so people can connect to send mail to your internal users.

ISP Servers:

A few changes need to be made on this side as well.

You should request a change to your DNS record (as held by your ISP).

The MX record for mail.abcd.com should be changed to point to the public IP address of your exchange server. That will allow internal users to recieve e-mail to abcd.com via the exchange.

If necessary the MX record for mail.abc.com should also be updated to point to the exchange server.

Be aware that DNS changes take time to propogate across all DNS servers. Your users should continue to recieve e-mail via the POP e-mail box at the ISP as well as via the Exchange server for at least a week after the DNS changes have been made.

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by sach_shin2001 In reply to

Hi ,
I have tried to clear your doubts. Please help me in solving the problem.

One suggestion I want to give is,
Can we use ETURN to specify a different domain name to receive the mails from on ISP?s exch1 server?
See, the problem is something like this --- If a company has one internal domain name, and a different registered domain name, how does the company receive the mails and send the mails?

Just a couple of questions first to clear up the assumptions I made while writing this.

abc.com is a local domain with no public records (internal only)?

Right now, yes. It does not have public ip address. But it has internal ad, DNS with name abc.com, and plan to have an exchange server with the name exch2.abc.com.

abcd.com is the public domain with a record elsewhere (external domain)?

Yes, abcd.com is a public domain (registered domain name) and has existence over the Internet. It has taken mailing service (let us call it exch1) from ISP
Both abc.com and abcd.com belong to same company, and users in abc.com were using outlook to download mails from ISP?s mail server.

Does all incoming e-mail for the domain abcd.com want to be recieved by the exchange server?

No. Since these 2 domains are situated at 2 different places, people from abcd.com want to access the ISP?s mail server using outlook. Hence that name will remain. But people from abc.com now want to have their mails retrieved from exch2.abc.com.Althaugh these users will want to have same email address e.g. ppp@abcd.com (i.e. if somebody sends mail to ppp.abcd.com, it will be received by ppp.abc.com)

Do all internal users need to be able to send out of their e-mail address on the abcd.com domain?

Yes, ppp.abc.com want to be able to send mail as ppp@abcd.com and also want to receive the mail as ppp@abcd.com. But remember, the mailbox should be on exch2.abc.com and not on ISP?s exch1 server.

Okay, these are with those above I also assumed that abc.com is the name of your Active Directory DNS as well.

To set this up, in my opinion the best way would be:

Exchange Server:

On the Exchange Server add an SMTP address for each mailbox as <username>@abcd.com. This should be the default (reply) address.

E-mail addressing for abc.com is unnecessary unless I misunderstand how your domain is set up.

If abc.com is also an external address you wish to recieve on then add that to the list of addresses on each account so the users can recieve on it. The address it sends as is determined by the default address for each user.

The Exchange server also needs to be publically available on port 25 so people can connect to send mail to your internal users.

ISP Servers:

A few changes need to be made on this side as well.

You should request a change to your DNS record (as held by your ISP).

The MX record for mail.abcd.com should be changed to point to the public IP address of your exchange server. That will allow internal users to recieve e-mail to abcd.com via the exchange.

If necessary the MX record for mail.abc.com should also be updated to point to the exchange server.

Be aware that DNS changes take time to propogate across all DNS servers. Your users should continue to recieve e-mail via the POP e-mail box at the ISP as well as via the Exchange server for at least a week after the DNS changes have been made.

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by ChrisDent In reply to Exch 2000 with different ...

This one will be a bit long...

Your system, as you describe won't work. You can still create a system that does work though.

1. MX Records

As before, MX records are used to find the e-mail server responsible for the domain.

This E-mail server is responsible for all addresses on the domain, if a server asks for a user and the owner of the domain can't answer it'll bounce.

This applies whether you set the MX record to failover or load balance mode.

Whatever happens, whichever server answers it must know what to do for each valid e-mail address on the domain.

MX records can't be used to create a split domain.

2. Local DNS vs Public DNS

Local DNS in this case is the DNS system and objects present on your private internal network.

You definately don't want this domain name to be public, or, if possible, even potentially public.

I personally advise the following naming scheme for internal domains <companyname>.local. Of course this depends on the complexity of the domain, so it would expand outwards to <sitename>.<companyname>.local. as necessary.

This gives a domain you can be totally responsible for that won't conflict with any potential public naming.

3. E-mail Systems and Domains

Its important to realise that e-mail domains can't be split.

One Server must be responsible for all e-mail of a domain.

The reasons for this are fairly straightforward given the methods MX uses to find the server in the first place.

4. Exchange and E-mail Addressing

The address you give the Exchange system is entirely arbitary.

This address is defined in the Default Recipient Policy (in system manager).

This address can be anything you like, and you must make Exchange responsible for all e-mail to that address if you wish to recieve (if you don't it assumes something else is and denies reciept on that address).

Exchange of course doesn't use SMTP for internal mail processing, that is performed by the X400 address.

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by ChrisDent In reply to

5. E-mail Gateways

An E-mail gateway is a mail server that sits in front of all other e-mail servers and forwards e-mail to the correct servers based on a set of rules.

This system would work for your e-mail system as follows:

Gateway knows everything about all users at abc.com.

Exchange Server knows everything about all users at abcd.com (this domain will only be used internally).

Gateway forwards e-mail for users on the Exchange server to an address at abcd.com.

Each account on the E-mail Server has an address for abc.com, which is set as the default address.

In the Default Recipient Policy this address is defined as an Address the Exchange Server is not responsible for.

For Exchange Users it recieves on the @abcd.com address set. For @abc.com it sends the e-mail back to the gateway server.

Because of the way DNS works you would want to avoid using a sub domain (ie @exch.abc.com) it wouldn't send out e-mail correctly from that.

6. The Rest

Along with all that above it would also be possible to have your external users use the Exchange server as a POP3 server rather than the ISPs.

That option certainly strips out the complexity of the system you are currently trying to achieve.

Part of the advantage of that method is that if the second site (or external users) ever get their own Exchange server you could add a second site to the Exchange structure and simply move the e-mail boxes to the other server.

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