Exchange design question

Hi Experts,

I have a client who owns multiple sub-companies, and a single Forest, domain Windows 2008 R2 with an Exchange 2013 on premises organization. Client has several authoritative domains for all their subsidiaries, and client uses MessageLabs as spam gateway. When a client sends an email to basically sends email to an external MX record managed by our external DNS provider, then redirects all email flow through Message Labs, then email is forwarded to our external firewall, then external load balancer, then Exchange 2013 edge servers, and finally email is delivered to mailbox servers.

The request that I have is, the company is looking to split or separate the companies in terms of email, where each one has their own SMTP in and OUT, and there is no confusion in terms of administration. Presently, if a company’s A employee encrypts an email with message labs, the client receives it on behalf of Company’s B.  This is because that is the default and only allowed domain through message labs.

Can you please summarize all steps required to separate emails organization in terms of Exchange, firewall rules, AD, MX records, spam gateways, and so on ?

Should we need to create new MX records, and more servers to separate companies?

Please, summarize high level steps for all activities required? Firewall, MX records, spam gateway, AD forest, domains,  and anything that I could missed.
Jerry SeinfieldAsked:
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Will SzymkowskiSenior Solution ArchitectCommented:
This is because that is the default and only allowed domain through message labs.

If this is true then there is a huge limitation with Message Labs. Do they offer multiple domains? Natively in Exchange you can have multiple primary domains for your users, etc. The limitation here is Message Labs.

It would be much easier to simply see if Message Labs supports more than one SMTP domain. If they do then it might be worth the cost to go that route.

If you do not you will need to setup a completely new Exchange infrastructure (new servers, MX, etc). There would be a lot of work envolved so i would start with message labs and see if it is possible to have multiple SMTP domains.


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Hello WorldCommented:

As Will mentioned, we need ensure message can be redirection correctly with Message Labs.
If so, we need set individual internet face CAS or site for each sub company, meanwhile, relevant MX and A record for each SMTP name and site. For Exchange configuration, we need configure external URL for each VD. Here's an article about redirection, for your reference:
Jerry SeinfieldAuthor Commented:
I've requested that this question be deleted for the following reason:

Will SzymkowskiSenior Solution ArchitectCommented:
I beleive i have provided enough info to make a deecision based on what you are asking. You cannot simply close this question using N./A as your reason.

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