Exchange/AD domain names

Probably a simple question, but hey, they all are if you know the answer!

I'm installing AD and Exchange 2003 in a test lab.  I've already installed AD based on advice I've gotten here at EE and also other places.   It was suggested that while installing AD I don't use a 'real' domain name. Meaning if my real domain name is, I should use mydomain.local as the domain name for AD. This is exactly what I did.
Now, after having installed Exchange and setting up users, it looks like the only domain name I can pick for those users is @mydomain.local.   Of course, I want my users email addresses to be
Is there some mapping I need to do someplace to map  xxx@mydomain.local to
How will others from outside of my network find (for example) when the email address on my Exchange server for 'mike' is mike@mydomain.local?

Is this something I need to set up in DNS and if so, how?
Is this something I need to configure in Exchange?

Who is Participating?
Brian PierceConnect With a Mentor PhotographerCommented:
There are pros and cons for having a different internal and external name and advice differs - I tend to prefer the 'keep them seperate' approach.


which will sort out your current issue.
SembeeConnect With a Mentor Commented:
I have done both and the choice of whether to do either is probably one of the most religious issues in the IT industry.
I am in the public name used internally. That doesn't always mean I use the same name as on email, if the client has a shorter name that they own then I will often use that. I am very much a fan of the shortest name possible when selecting the domain.
All of my test environments are based on a real domain, but I do use a sub domain - so, etc.

You have to add the additional domains to recipient policy, as the link above explains. DO NOT remove the email address for your Windows domain (the .local address) as that can cause problems.

Sembee is right in that this is one of the biggest points for discussion when planning a domain AD infrastructure.
i also prefer the short public domain aproach, with one exception.
if it is likely that there is going to be a name change in the near future or likey that there are going to be aquisitions of other companies that will result in domain name changes.
if this is likely to happen i will go with a generic domain name, because there are huge implications on the manner in which a domain has been set up. with things like the exchange server installed on a DC preventing the renaming of the AD domain, amongst a thousand other issues that do crop up. if it is a small environment and it is not likely to grow, or if the domain name is well established then used the public.
i am working with a multi national client now who has to rename the domain due to a merger, and it is literally going to take about 4 to 6 months to get to a point where the rename is possible.
michaelshavelAuthor Commented:
Thanks very much to all of your for you comments.
I'm going to go with the different public/private names mostly because I'm new to this and I think it will be easier to keep track of things.

I have another question about DNS but I will include that in a new question.

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