Configuring Delegate Mailbox Access

Document created by user.oxriBaJeN4 Employee on Sep 14, 2015Last modified by user.oxriBaJeN4 Employee on Jan 18, 2018
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This guide describes how to configure delegate mailboxes to provide end users with access to multiple email archives. For example:

  • A user gets married and their email address changes when their name changes. Once a delegate mailbox has been configured, the end user would be able to search for all the messages associated with their new and old account.
  • If using a generic address (e. g. users can have this generic address added as a delegate mailbox. They are able to view emails that are not emailed for / to themselves.

Users can access delegated mailboxes from Mimecast's end user applications. Delegate mailbox access does not include emails that have not yet been archived (e.g. accepted emails).

You must have Full Administrator, or Super Administrator access to delegate permission to mailboxes. See the Understanding Administrator Roles page for more information.

Excluded Messages


End users are able to change message sensitivity levels to email in Microsoft Outlook. If the sensitivity is changed from the normal status (i.e. to personal or private) and the message is submitted to Mimecast, the Sender Privacy Policy applies. This policy does not display in the Administration Console, and is enabled by default for all messages. You can verify if this policy has been applied using the Email Receipt / Delivery View.


If this policy has been applied to a message, the following occurs:

  • The message is not displayed in Delegate Mailboxes.
  • The policy is not apply retrospectively. It only takes effect when the message is sent through Mimecast (or uploaded through journaling or ingestion).
  • The message is not replicated to Mimecast through Mailbox Folder Replication.
  • The message is still accessible to the original user in their mailbox archive search, and to administrators through the Administration Console archive search, or eDiscovery Cases.


Manually Adding Delegate Mailboxes

Multiple delegate mailboxes can be added by repeating the steps listed below for individual addresses, or by following the instructions in the "Importing Delegate Mailbox Access" section below.

To manually configure a Delegate Mailbox:

  1. Log on to the Administration Console.
  2. Click on the Administration toolbar button. A menu drop down is displayed.
  3. Click on the Directories | Internal Directories menu item.
  4. Select the appropriate Internal Domain.
  5. Click on the required Domain. It's email addresses are listed.
  6. Click on the Email Address to be given delegate access. This displays the Address Settings.
  7. Click on the Add Delegate Mailboxes button from the top toolbar. This displays any current delegates for the selected primary address.

    Add Delegate Mailboxes
  8. Click on the Add Delegate Mailbox button to select the delegate mailbox address.

    Delegate Mailbox Address
  9. Click the Lookup button to the right of the Delegate Mailbox field.
  10. Type the Name or Email Address of the user in the Search field.
  11. Click on the Search button.
  12. Select the Email Address from the list of results.
  13. Click on the Save and Exit button.


Importing Delegate Mailbox Access


You can import access settings for delegate mailboxes by using a formatted spreadsheet. We only accept spreadsheets in .XLS format, and the layout of the import is critical for data to import correctly. An example of the correct configuration is shown below. For guidelines on the spreadsheet import format, read the Adding Users Using a Spreadsheet Import page.


Import_Spreadsheet_Delegate_Mailboxes.pngIn the example on the right, two primary addresses (, and three delegate addresses are defined. Two delegate addresses have been assigned to the same primary address (i.e. has two delegates of and


The key points to note when creating the spreadsheet are:

  1. The spreadsheet must include two key fields for the correct configuration, namely "primaryaddress" and "delegateaddress".
  2. Both the primary address and delegate address must already exist in the internal domains of your account.
  3. You can configure multiple delegates to the same primary address. Each delegate must appear as a separate entry in the spreadsheet (as shown in the example above).

A primary address cannot be a delegate address to itself.

To perform the import, prepare the spreadsheet and associated data before starting the import process. The column headings listed below should be used:

Column HeadingTitleDescriptionExample
primaryaddressEmail AddressThis must be a valid email address, and must not contain spaces, surrounding quotes.
delegateaddressNameA valid internal email address (formatted as above) for the delegate mailbox. If you wish to assign more than one delegate to the same primary address, create a separate line in the spreadsheet for each new


  1. Log on to the Administration Console
  2. Click on the Administration toolbar button. A menu drop down is displayed.
  3. Click on the Directories | Internal Directories menu item.
  4. Select the appropriate Internal Domain.
  5. Select Import Delegate Mailboxes button from the toolbar.

    Import Delegate Mailboxes

  6. Click on the Choose File button to select the required spreadsheet file.
  7. Click on the Preview Changes button on the toolbar to validate the entries in the Excel file. The results are displayed.

    Preview Delegate Mailboxes
  8. If there are no errors, the Accept Import button is displayed in the toolbar. Select this to start the import process.


The import may take several minutes to complete, depending on the volume of data being imported. Once the import has completed, the delegate address will be added to the Delegate Mailbox listing for the primary address.


Manually Removing Delegate Mailboxes


To remove a delegated mailbox:

  1. Log on to the Administration Console
  2. Click on the Administration toolbar button. A menu drop down is displayed.
  3. Click on the Directories | Internal Directories menu item.
  4. Select the Internal Domain.
  5. Select the User whose delegate mailboxes you want to remove.
  6. Click on the Add Delegate Mailbox button on the toolbar.
  7. Right click on the delegate mailbox to be removed.
  8. Click on the Delete Delegate Mailbox menu item from the popup menu.


Log Files


Following a successful import, the delegate and primary account details can be viewed: 

  1. Log on to the Administration Console
  2. Click on the Administration toolbar menu item.  A menu drop down is displayed.
  3. Click on the Account | Audit Logs menu item. 
    Delegate Mailbox Logs

This information is also sent via email notification to the super and full administrators.


See Also...


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