Configuring Delegate Mailbox Access

Document created by user.oxriBaJeN4 Employee on Sep 14, 2015Last modified by user.oxriBaJeN4 Employee on May 2, 2017
Version 10Show Document
  • View in full screen mode

Delegate Mailboxes can be used to provide end users with access to multiple email archives, which may be required in certain circumstances such as:

  • Example 1:  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 emails associated with their new and old account.
  • Example 2: If using a generic address e. g., users can have this generic address added as a delegate mailbox. They are then able to view emails that are not emailed for or to themselves.

Delegate mailbox access does not include emails that have not yet been archived (e.g. accepted emails).

Users can access Delegated Mailboxes from Mimecast end-user applications.


Excluded Messages


End users are able to change message Sensitivity levels to emails within Outlook.  If the Sensitivity of an email is changed from the Normal status (i.e. to Personal or Private), and the message is submitted to Mimecast, the Sender Privacy Policy will apply.

This policy does not display in the Administration | Services | Gateway menu, and is enabled by default for all emails. You can verify if this policy has been applied using the Email Receipt / Delivery View. The feature is available to customers utilizing the latest gateway.

If this Policy has been applied to an email, there are two end effects:

  • The message is not displayed in Delegate Mailboxes
  • Note that this Policy does not apply retrospectively, but will only take effect when the message is sent through Mimecast (or uploaded through Journaling and Ingestion)
  • The message is not replicated to Mimecast through Mailbox Folder Replication.
  • The email is still accessible to the original user within their mailbox Archive Search, and to Administrators through the Administration Console Archive Search or eDiscovery Cases.


Manually Adding Delegate Mailboxes


To manually configure a Delegate Mailbox, the Administrator should be logged onto the Mimecast platform with sufficient administrative access.

  1. Click on the Administration toolbar button.
  2. Click on the Directories | Internal Directories menu item.
  3. Select the appropriate Internal Domain.
  4. Search for the primary address (i.e. the email address of the user who is going to log on and perform the search.)
  5. Open the Email Account. This displays the Address Settings:

  6. Click on the Add Delegate Mailboxes button from the top toolbar. This displays any current delegates for the selected primary address.

    This button is only available when logged in as an Administrator with protected permissions.

  7. Click on the Add Delegate Mailbox button, which allows the Administrator to select the delegate mailbox address:
  8. Click the Lookup button to the right of the Delegate Mailbox field. In the Search dialog box, type in the name or email address, and click the Search button.
  9. Select the email address from the list of results.
  10. Select the Save and Exit button.

Multiple delegate mailboxes can be added to a Primary Account by repeating the steps above.

Import Delegate Mailbox Access


If an Administrator with sufficient administrative access is able to configure a Delegate Mailbox, they can also import access settings for Delegate Mailboxes by using a formatted spreadsheet. Mimecast only accepts 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 Mimecast guidelines on the spreadsheet import format, please read the full article.




In the example above, two primary addresses (, and three delegate addresses have been defined. Note that two delegate addresses have been assigned to the same primary address (i.e. has two delegates - and


The key points to note when creating the spreadsheet are:

  1. The spreadsheet must include two key fields for correct configuration - primary address and delegate address
  2. Both the primary address and delegate address should already exist in the Internal Domains of your Mimecast 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 can not be a delegate address to itself.

Updating Delegate Mailbox Access with an Import


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
primary addressEmail AddressA valid email address, which must not contain spaces, surrounding quotes.
delegate addressNameA 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. Click on the Administration toolbar button.
  2. Click on the Directories | Internal Directories menu item.
  3. Select the appropriate Internal Domain.
  4. Select Delegate Mailbox Import from the toolbar.

    This button is only available to Administrators with protected permissions (e.g. Super Admin or Full Admin role).


  5. Navigate to the formatted spreadsheet by selecting the Choose File button to upload the file

    The Excel file format should comply with the requirements of file Imports.

  6. Select Preview Changes from the toolbar to validate the entries in the Excel file:

  7. If there are no errors, the Accept Import menu is displayed in the toolbar. Select this menu option 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. Click on the Administration toolbar button.
  2. Click on the Directories | Internal Directories menu item.
  3. Select the Internal Domain.
  4. Select the User whose delegate mailboxes you want to remove.
  5. Click on the Delegate Mailbox option.
  6. Using the search field, Search Within radio buttons, or the View menu, locate the appropriate items in the list:

  7. Use the check boxes to the left of each row to select the appropriate addresses.
  8. Click the Remove Selected Delegate Mailbox button from the toolbar.




Following a successful import, the delegate and primary account details can be viewed by navigating to Administration | Account | Audit Logs. This information is also sent via email notification to the Super and Full Administrators.



See Also...


4 people found this helpful