Multiple SMTP domains on one exchange server

By boomio ·
Hi all,

I am currently trying to set up our exchange 2003 server to host email for about 8-9 domains. Our setup is that we have one domain controller(w2k3), which hosts all users for 4 different in-house companies. Basically what I need to set up exchange to handle all the seperate smtp domains. Is it possible to use exchange to set all the users working for, to adopt the email address <username>, and etc etc for,
Also, we are currently using pop3 accounts and pst files but we would like to migrate to using server mailboxes, is there an easy way to do this

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All Answers

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to host multiple domains

by CG IT In reply to Multiple SMTP domains on ...

for email, you also have to host their DNS or have some way in which the MX records point to your public address.

that's why most hosting companies don't host email services for other people's domains. First the administrative effort for each DNS and Exchange isn't cost effective. Second is hardware resources. You can't host multiple domains with multiple email services without a server farm. One box or even 2 boxes just won't cut it. Third is CALs. Even if you were able to host domain names using Linux or Novell DNS, Exchange will require CALs for connections from every user in every domain.

A better bet would be an email platform other than Exchange Server.

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Hosting of DNS

by boomio In reply to to host multiple domains

Sorry, just reading back, I can see that i probably didnt explain the situation correctly. We have an external company that hosts our dns and MX records for all the domains we own, I just need to facilitate the email for all those domains in here. i.e we just get the hosting company to redirect all emails to,, etc to our email firewall on our new exchange server. But we need to have the exchange server set up first to handle all the domains we own. Apologies if this makes no sense, I only do desktop support and have no experience of any version of exchange server.

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Why do you need multiple domains?

by heathj In reply to Hosting of DNS

Do they actually need to belong to a different domain or is this just a way to fix email? We're smaller, but we setup all users in the same domain and then they get an SMTP address added in the Exchange properties for,, etc. as default for each separate domain.

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Re: Why do you need multiple domains?

by cparrish In reply to Why do you need multiple ...

And how did you accomplish this? I have a company that is being integrated in to my current company and they need to retain their SMTP address when sending Email out.

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multiple domains

by moracca In reply to Re: Why do you need multi ...

I think two issues are getting confused here. One is actual domains, such as having a computer a member of a domain, and the other is having exchange except mail for various internet domain names.
Basically, you just need to configure exchange to accept mail from each domain (exch system manager -> recipients -> recipient policies -> default policy -> email addresses (policy) tab -> add your domain). Now exchange will accept mail addressed to each of these domain names. You simply need to make sure that the DNS records for each domain point the MX record to your firewall's wan IP address.
Then you would just add the appropriate email address for each user in active directory. Mail sent to any of the domains will arrive in that user's mailbox.
Things get hairy when trying to reply to those emails if users have more than one email domain (only one can be set as primary, and that is what it will send out as). Third party software exists to work around this flaw however. If each user has only one domain though, it shouldn't be an issue.

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Sounds familiar...

by jim.dolan In reply to multiple domains

we are attempting the same setup. I have 3 public domain names due to mergers and acquisitions. all public DNS and MX records now point to my in-house server. what we WANT to do is have, and all go to the SAME user mailbox. I added the email addresses to the user, but all emails to domains other than (our original) are being rejected.

any ideas?

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I have set up the same thing

by Doug Buck In reply to Sounds familiar...

I understand what you are takling about. You want someone to be able to send an email to, and send an email to both emails would go to user1.

This is an article for exchange server 2000, but it applies to 2003 as well. Follow the second way of setting it up. It is much easier than setting up multiple vitrual servers.

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