Microsoft Exchange Server 2013 : Mailbox management - Setting mailbox permissions (part 3) - Mailbox auto-mapping through Autodiscover

Mailbox auto-mapping through Autodiscover

Granting Full Access to a mailbox is one thing; a user being able to open the mailbox to access it is quite another. The traditional approach has been to modify the user’s Outlook profile so that the mailbox is opened along with the other resources available to the user. To do this, edit the profile, select More Settings, and then choose the Advanced tab (Figure 4). Enter the name of the mailbox that should be opened.

Figure 4. Telling Outlook to open another user’s mailbox

This approach works at the expense of requiring an intervention by the user or an administrator to make sure that the profile is correctly configured. Fortunately, some Autodiscover magic happens to detect when users have Full Access to other mailboxes. Whenever a user is granted Full Access to a mailbox, Exchange updates the msExchDelegateLinkList property for the mailbox’s Active Directory account. This property holds the distinguished names of all the accounts that have Full Access to the mailbox.

When Autodiscover runs, it checks Active Directory to find whether the account for which it is running has access to any other mailbox. If the account is listed in msExchDelegateLinkList for any other account, Autodiscover includes these mailboxes as alternates in the XML manifest it provides to Outlook; Outlook then inserts the mailbox in the resources it shows to the user. This feature is called mailbox auto-mapping, and it only works when Full Access is assigned to individual users rather than to groups. The same mechanism is used to provide Outlook with information about site mailboxes the user is entitled to open.The information Autodiscover provides to Outlook looks like this:

<AlternativeMailbox>
        <Type>Delegate</Type>
        <DisplayName>Contoso PR queries</DisplayName>
        <SmtpAddress>ContosoPR@contoso.com</SmtpAddress>
</AlternativeMailbox>

Sometimes, you might not want a mailbox to show up automatically in Outlook, so auto-mapping can be disabled if necessary by including a parameter when you run the Add-MailboxPermission command to assign Full Access to a mailbox. For example:

Add-MailboxPermission "Sales Enquiries" –User TRedmond -AccessRights FullAccess -AutoMapping:$False

This command assigns Full Access to the mailbox to the nominated user but does not populate the msExchDelegateLinkList property for the account. Full Access remains undetected by Autodiscover, and Outlook is not instructed to open the mailbox. If necessary, the traditional approach can be used to open the mailbox.