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Active Directory Migration, 2 Companies merging and forming 3 companies and want to bring in another one

Hello Experts,

Thanks for all of your help with the last problems, I had. I need a step to step guide on how to achieve this objective. Our company B is currently bought out by company A. Basically the CEO who invested in our company is fixing to create a Holding company called C and Company A and B will reside under it like in the diagram showed below:

Company C - Will have own email But will share information like CRM and Tools with Company A and B.
Company A   - Will have their own email like a@companya.com, but will share information like CRM with Company C and A
Company B - Will have their own email like b@companyb.com,  but will share information with Company B and C

Currently Company A and B have their own domain and forest. Company C domain hasnt been created.

I was thinking to create

Company C domain and email first > 

Create Company A as a Child Domain but confused about how to create email since emails have to be the same and cant be test@companya.companyc.com.

Create Company B as a Child Domain but confused abt emails again, how to keep them a same.

We might be bring Company D and we want the solution scalable so it would be easy to integrate Company D when that comes in.

Need Advice and Help on how to go about this desperately. I know tools like ADMT can be used for migrating users from one server to another but what can we do to retain emails when the domain willl be changing.

Thank you, Experts
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1 Solution
from an AD point of view its fairly simple...you should probabaly check out this for your AD structure....i dealt with this previously


Now from an exchange point of view its simple either way....you basically allow your exchange server to host multiple domain names....its doesnt care about the internal AD structure from a name point of view...i have a single AD and host 4 sepeare company names within exchange.....

Its easy, you just base your email addresses on recipient policies
mshaikh22Author Commented:
Morning Jay,

I am sorry that I havent been able to update  on my end. I been researching about this and found that we have a sql server also that connect to a CRM that both companies will be sharing in the future. After a meeting with our support company. They suggesting that we go the domain trust route which is establish a trust between two domains.

Currently Company A users are connected on company B domain since they are working from the same building as Company B and Company A servers are connected offsite at the data center.
Company A users are remotely connecting (Terminal Services)  to their servers. They have access to Company B CRM System and their Outlook to book rooms.

Going forward, you were suggest to use one exchange server which would Company B exchange server and add Company Email as an additional Domain.

(I know how to add the additional domain basing them on email addresses on recipient policies
, but do we have to add an additional smtp connector since both emails have different MX Records).

And use each company as a organisational unit in AD. Thats mean do we need to redesign the AD structure since the company names are changing.

Should I take the Parent and Child Domain route. Could you please give a step by step process on how to achieve this, cause I hope im not confusing you caz this thing is all new to me.

If you could help me out, I would really appreciate it this. I hope I didnt confuse anyone.
mshaikh22Author Commented:
Thanks a lot for your help, Jay. I read the link again and its has answered most of my questions.

Thanks again.
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hey mate - been flat out 0 have been meaning to post and still will - let me sit and have a proper read and ill see what i can see for you bro
mshaikh22Author Commented:
Thanks a lot for getting back to me, Jay.

Basically I had a meeting with our COO and he was throwing all sort of questions at me like.

How many email domains can exchange 2003 standard hosts, cause they are planning to acquire more companies in the future.

Basically this is what I am thinking abt doing

Plan A

At the moment they are three companies

Current Network Setup
All companies will be working from one site and will have satellite office and remote users connecting.

se - Holding Company - New Holding company needs email that is se.com. Domain is not setup. Users are based in the fpl building but will be executive users who are not setup yet.

fpl- Company A - It has a different email domain which is fp.com. The exisiting domain running on the network in the building

cplc- Company B It has a different email domain which is ctm.com.

The First company to be acquired 3 months ago and users are in the fpl building.
Cplc pcs are connected to fpl domain and their TS server and exchange server is based offsite which they use terminal services to access their cplc domain and ctc email.

xyz- Thinking of acquiring a possible company in the future.

The Companies are not going to be sold out in the future. All three companies will be based in one building and want to share Exchange emails (All three companies will have different emails), calenders,CRM, Sage accounts. They will satellite office but that will be decided later. I need a solution that scalable and can be achieved within budget.
We dont have that much of a budget in place.

Intially, I was thinking of getting a new server and creating a Single domain using name of se.com.

Creating an organizational unit called fpl on the se server.

Once the AD structure is builting. Migrate all of the AD info from fpl domain controller using ADMT to se.com server .

After that migrate all of ctm users  using ADMT on to Se server and create an organizational unit called

Get another server, install exchange on there and join it to the se.com domain.
Add fp.com email domain and ctm.com email domain in the recipient policy.

*The thing i was thinking that how many MX Records will exchange email and hence how many smtp email domain does it support as you stated in your last reply that you currently have an exchange server that has 4 different domain emails.

Do we have to disconnect all pcs from the fpl domain and join them on the se.com

I seen a tool from microsoft that renames the exisiting domain, does it work well with exchange

Plan B

Use the exisitng  server that has fpl domain and add ctm.com and se.com as a OU.
Migrate all users using ADMT from ctm to fpldomain.

Use the exisitng fpl exchange server and add ctm email and se.com email as receipient policy.

Exchange is standard here too. I dont know if we need more than one information store.

I think I am confusing myself too much. Since I have read your posts, im begining to get a better picture of what needs to be done. But if I can get your input on this and the best way to move forward. That would be greatly appreciated.

Thanks a lot for your help on this Jay. Appreciate it greatly. I will wait for your post on this. I just posting this so you get a better idea of our network setup.

Thanks again,



Hey mate :)

K lets take a look at this - Basically, you have a very similar setup to myself from a company point of view so this isnt to foreign a scenario to me at the moment.

What i have for my AD setup as far as companies go is as follows

Holdings Company domain.local - now i have 4 child companies that are owned by the holdings company. Seeing we were never going to sell them off etc, and the boss could guarrantee they would never be segmented, i was able to decide on a single AD Structure the same as you have....So i have a seperate OU at the root of my AD for each company, which i then have the relevant OU structure under that....

Im also in the same boat as you where i have staff from each different company working in the same office and in multiple locations etc etc so thats all good

For your migration, i would avoid the rename tool, it will break your domain. Decide on the root - or if you have time and hardware, then start a new forest and migrate all the other users across with ADMT...but that is a huge task and if you have a root in place already, then you are much better off just using that and migrating people in as you go....You will have to join every machine into the domain, and it can be a long task :)

Exchange will be able to cope with as many email domains as you can throw at it....the beauty of exchange is that it doesnt rely on or have to match your AD structure...you can simply keep adding email domains ato it and away you go

Let me know if you want any clarification on anything there - ive been down this path so fire any questions you have
mshaikh22Author Commented:
Hello Jay,

Thanks a lot for getting back to me on this. Your detailed reply explained everything already.

I agree with you that it will be best to use the exisiting fp.local domain, since it is already set and all machines are connected to that domain.

I might have questions when I start implementing the process. But this would take months for management since it needs  to agree with our plan. And there's too much politics in my companies unfortunately. Fingers crossed and let see how it goes.

Thanks again for all of your help.

Have a good weekend and I will keep you posted on what goes on. I ll open another post since I have closed this one, sorry about that.

Have a good night,



no worries at all mate, let me know how you go, ill be around :)

mshaikh22Author Commented:
Will do Jay.

Thanks again.

mshaikh22Author Commented:
Hi Jay,

Hope you had a lovely Christmas. Sorry I havent heard anything from my boss regarding the proposal I presented. I guess I'll hear about it next year when I go back to work.

Happy Holidays and speak to you next year.

Have a good one.

and you too mate - thank you :)

Enjoy the break champ


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