How a single exchange on a domain can be use by other domains RRS feed

  • Question

  • Subject: How a single exchange on a domain can be use by other domains ?

    Dear all,

    first of all thanks a lot for visiting for this question.

    firstly I present current layout.

    1) I have a domain .  e.g.,      

          domain name: domainA.B.C  ,  

         Exchange Server 2013 FQDN:     EXS.domainA.B.C  (

         domain controller is   :     DC.domainA.B.C     (

         IP range:

        users examples:       Umer@domainA.B.C,  Ali@domainA.B.C  

    2) I have other 10+ independent sites  with different domain and different IP range. 

    all sites connected though VPN. and can ping each other.


    sites configuration example.

    2.1) site1 

              domain name :     domainE.F

              Domain controller name:     DC.domainE.F  (

             IP range :

             user example:    Ahmed@domainE.F ,    Fahad@domainE.F , ....

    now situation is that

    my Main Office has only exchange server 2013 installed and all users and department on main office have their emails.

    Q1: I want other sites use this exchange server (MXS.domainA.B.C) .

    Q2: what are possible methods can be ?

    Q3:  can I use single Exchange server (MXS.domainA.B.C) to store mailboxes of other sites and other sites use this Exchange server with their user names.

        Ahmed@domainE.F ,    Fahad@domainE.F   but in  MXS

    what I tried :

    I added "accepted domain" as "domainF.E"

    I added emails policy and add email address format  "smtp@domainF.E" and applied

    but I could not find way to add mailbox Ahmed@domainE.F ,    Fahad@domainE.F 

    and what else I need to do and why i don't find domain: "domainE.F" in "MXS.domainA.B.C" mailbox ?

    Thanks a lot in advance for helping me.


    1) all networks (,, ..... ) can ping each others.
    2) all domains are separate. does not belong to single forest.  in other words there were separete sites and now connected thorugh VPN and can ping back and forth.

    Thursday, December 29, 2016 8:51 AM

All replies

  • Hi

    If you have single forest and single active directory and multiple domain then it is possible. If multiple forest then go for hosted exchange setup.

    Thursday, December 29, 2016 10:36 AM
  • Hi,

    you should configure trusts between domains, and then you can create a linked mailboxes

    Manage linked mailboxes

    Thursday, December 29, 2016 10:48 AM
  • Hi,

    Since "all domains are separate. does not belong to single forest." You need to set up a two-way forest trust.

    And then create linked mailboxes. All you have tried is adding proxy address for users in domain DC.domainA.B.C. It will not let users in domain DC.domainA.B.C to find users in DC.domainE.F.

    Best Regards,

    TechNet Community Support

    Please remember to mark the replies as answers.
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    Friday, December 30, 2016 3:22 AM
  • The Active Directory domain doesn't have to be the same as the SMTP domain.  They are completely independent.

    When you create a mailbox it gets an e-mail address policy applied.  If you want to change the SMTP address, clear the "Automatically apply e-mail address policy" (or whatever it is--I'm reciting it from memory) checkbox and then change the e-mail address to whatever you want it to be.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    Friday, December 30, 2016 7:44 AM