1 SBS Server w/ Exchange - Multiple Domains

I am not a networking expert, however I've been given a lot of networking responsibilities due to some staff problems...anyway....

We just purchased a new SBS 2003 server to replace an old NT / Server 2003 (domain trust) and Exchange 2000 rig.  The domain for the headquaters of the company is, say : ab.com.  We have 2 divisions of ab.com.

a.com and b.com.

Some users work for a.com and other users work for b.com.  Some users work for both a.com and b.com.  I need 1 exchange server with 1 pdc aka SBS 2003 to handle all three domains.  Specifically the mail from a.com and b.com.  ab.com mail is not important.

Some users need outlook setup with both email from a.com and b.com and when mail is sent out it is very important that it appears to be coming from a.com or b.com depending on the users preference.

I do not want to use 3rd party solutions.

I will setup "gateway" linux servers if need be.  I am much better in linux, but not I'm definatley not an expert.

How can I accomplish this goal.  Just lay it out for me, no specifics needed. :)
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Everything you do, try to do with the wizards.

That said, if you can't do it with the e-mail setup wizards, you can easily do this:

Then you can go to the account properties of each user and set the primary email for each user.  The primary email is the one that the user will APPEAR to be sending from.  Any SMTP address listed (that is also in the recipient policies) will be a valid email address.
Exchange is quite happy with multiple domains for receiving, but for sending it becomes more difficult.
Exchange operates on a principle of one account - one email address, and the default email address is the one that all email goes out on. While you can have as many email addresses as you life for receiving email, you can only send email out on one.

Third party tools that make this easier include Choose From: http://www.ivasoft.biz/choosefrom.shtml
However if you don't want to use third party tools, then you have to use multiple accounts and the from field.
This is basically a matter of creating an account for each email address that the user needs to send email from. Configure all of these accounts to forward their email to the primary account.
Configure all of these accounts so that the primary account has permission to send as that account.
Then use the From field to control which address the message appears to come from.




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