Microsoft Exchange and Blackberry Server Specialists

Two Domains One User

After introducing a second email domain to Exchange, you may be required to allow a single user to be able to reply from multiple domains. There are a number of techniques that can be used to achieve this.

  1. Two email accounts and use the "From" field in Outlook.
    This method does not involve any third party products, but does require that the user selects the correct account for the email to come from.
    1. Create two (or more) accounts - one for each email address that needs to be used.
    2. Modify the email address properties of each account so that the correct email address is the primary. You should disable the option "Automatically update email addresses based on email address policy".
    3. Decide which account is going to be the primary user account. This is the account that all email is received on and is the account which the user logs in to the network using. Put strong passwords on to the other accounts so that they cannot be abused.
    4. Grant "Send As" permissions on each of the additional accounts to the primary account. This setting is changed using the "Manage Send As Permission" option in the Exchange Management Console.
    5. On the Mail Flow Settings tab, choose "Delivery Options" and set a "Forwarding Address" to the primary account. Do not select the option to deliver to both the forwarding address and the mailbox. .
    6. On the primary account, configure Outlook in the normal way. Then open a new message and activate the From field from the View menu.

    The user simple clicks on the From button and selects one of the other accounts from the list. If using a version of Outlook that supports "Auto Complete" then this only needs to be done once, as the Auto Complete feature can be used for future entries.
    You could also use a Macro (see below)

    All new email comes in to the primary account. No copies are stored elsewhere.

    Note - this method does not increase the number of CALs that you need for Exchange or SBS, due to the way that those products are licensed (at the time of writing).


    There are a number of issues with this method, which need to be taken in to account as to its suitability for deployment on your network.

    • Outlook Web Access Support.
      This method doesn't work in Outlook Web Access as OWA doesn't have support for the From field.
    • Identifying which address the email came to.
      In order to identify which email address was used, you have to look at the Internet headers of the email message to identify the original email address.
      One way round this is to NOT forward the email to the primary mailbox, but unless you are using Outlook 2010, there are no notifications for the additional mailbox.

    Other Accounts Visible in the Global Address List

    To allow Outlook to select the other accounts to use in the From field, they must be visible in the GAL. This may cause confusion for other users.
    A work around for this is to add the account to the user's local contact list. You MUST add the contact from the GAL, so it will need to be visible for a short while. Find the other account in the Address Book through Outlook. Right click on the address and choose "Add to Contacts". Outlook can now resolve the email address to the correct account.

    Macro for Email Creation

    If you decide to use the From field method, then you could use a Macro to create the email message with the From field already populated. Provide the user with a button and when they want to send an email as the other address, they simply click on the box. More information on creating the macro is here.

    Outlook 2010

    Outlook introduces the ability to have two sets of accounts in its configuration. This allows two sets of rules, two sets of notifications, two signatures. It does mean that two inboxes need to be monitored, and does not get round the OWA and Mobile Issues with the first technique, but it makes management of multiple email addresses a lot more straight forward.

  2. Third Party Application.
    A third party application has been written which may prove to be more acceptable to your users.
    It is called "Choose From" and can be found here:
  3. Another Third Party Application
    Yet another third party application that may resolve the problem is now available. ExtraOutlook ( allows two profiles to run at the same time. However do be careful with the application - if you have tools that send email via Outlook automatically it may send via the "wrong" account. It also can confuse desktop search applications, including the built in one within Vista.