Mimecast Synchronization Engine - Mailbox Storage Management

This article provides information and steps to assist with Mailbox Storage Management.

Mailbox Storage Management uses native Exchange entry points to identify and take action on email messages and attachments in Exchange mailboxes. Mimecast stored message data can be directly accessed from the Exchange mailbox. Allowing administrators to control the size of mailboxes on the corporate Exchange servers. Users can safely remove Mimecast archives from their Exchange mailboxes with end-user productivity options such as:

• Replacing message components with links to the Mimecast archive while leaving the message in its original location.

• Deleting messages and using the Archive Folders feature in Mimecast applications to view the message in its original location (Mailbox Folder Replication required).

Considerations

While message stubbing has useful benefits, there are long-term implications to be considered.

• All messages/attachments matching the definition are processed the first time a task is run. Depending on the number of items in the mailbox, this can take a long time.
• When a message/attachment to be stubbed/deleted is identified, the Exchange task requests Mimecast to check the message is archived and that the user of the requesting source mailbox has permission to access the message.
  • If the message is confirmed, it is stubbed/deleted.
  • If the message is not confirmed, the message is not stubbed/deleted.
  • Requests for messages not found can cause extended delays in processing time. It is important only to run mailbox storage management tasks when all Exchange messages are known to be in the Mimecast archive.
• Full message stub removes the message body from the Exchange mailbox. Consequently, users will no longer be able to use native Exchange client's search functions, such as Microsoft Outlook, to search for terms they expect to be in the body of a "stubbed" message. This isn't an issue for attachment stubbing.
• A Mimecast-supported version of Microsoft Outlook for Windows is required to retrieve stubbed messages and attachments. Attachment Stubbing with Universal Access is not affected by this issue.
• User-Initiated Stubbing does not require a definition and is created using an Exchange Task. Users will use Mimecast for Outlook to select which emails they want stubbed rather than candidates being determined from an admin policy. See further down this page for further details.
  The Mimecast for Outlook User Initiated Stubbing feature is controlled in Configuring Application Settings and is disabled by default.

Configurable Actions

Mailbox Storage Management can be defined as taking one of the following storage management actions:

Action	Mimecast for Outlook Required	Description
Message Delete	No	The full message, including attachments, is completely deleted from the Exchange Mailbox.
Full Message Stub	Yes	The message body and attachment components are removed from the message, leaving behind a small message skeleton linking to the Mimecast archive.
Attachment Stub	Yes	The message attachment(s) are removed from the message, leaving behind the message body and a small skeleton of the attachment(s) linking to the Mimecast archive.
Attachment Stub (Universal Access)	No	The original message attachment(s) are removed from the message, leaving behind the message body. Message attachments are replaced with an HTML attachment containing a link to download the original attachment from the Mimecast archive. No additional client software is required to open the stubbed attachments. This allows users to access stubbed attachments from any mail client while connected to the internet. You must consider that when a user forwards messages stubbed using this method to an external recipient, the stubbed attachment is forwarded as the stubbed HTML document, not the original file. The recipient can access the original attachment using the link in the HTML file, but the content of the original attachment isn't subject to any outbound Content Examination Policies. The links generated for the Universal Access Attachment Stubbing feature are both encoded and encrypted. For additional security, they aren't predictable or reversible in any way.

In some instances, only backup certain message classes, and not custom message classes such as Mimecast Stubs (IPM.Note.MimecastStub).

Creating a Definition

The settings used for the Mailbox Storage Management feature must be defined in a Mailbox Storage Management definition. In addition to specifying the Message Action type and the sizes of mailboxes to target, administrators can also specify the security and importance levels.

When creating Mailbox Storage Management definitions, many sections can be configured to make the selection of stubbed items as specific as possible. Configuring the main options within Mailbox Storage Management properties and ignoring the other available criteria is possible.

To create a Mailbox Storage Management definition:

1. Navigate to the Services | Exchange Services menu item.
2. Click on the Exchange Definitions drop-down list.
3. Click on the Mailbox Storage Management option.
4. Complete the available options as described in the table below:

Section	Field	Description
Mailbox Storage Management Properties	Description	Enter a meaningful description for your Mailbox Storage Management Definition. As several of these definitions may exist, the description is important to identify the correct definition. A good example would be: "Attachment only stubbing for emails older than 90 days".
	Test Run Only	Simulates the execution of the MCS task definition, allowing Administrators to view the impact of an MCS task without stubbing the affected messages.
	Message Action Type	Stub Full Message: The entire message is stubbed, including any attachments that meet the additional criteria. Stub Message Attachment: Only the message attachments are stubbed. Mimecast for Outlook is required to open Mimecast stubbed messages. Delete Message: Removes non-stubbed messages that are already matched in the Archive. Stub Message Attachment (Universal Access): Replaces attachments with a small HTML document containing a link to the original attachment in the Mimecast archive. Messages/message attachments will only be processed if they are confirmed to be available in the Mimecast Archive.
	Mailbox Larger Than (MB)	Allows Administrators to manage Mailbox Storage Management activity by restricting the task to only apply to mailboxes over a certain size. Setting this option to 0 (zero) will set the task to stub all messages that meet the additional criteria selected.
	Message Larger Than (KB)	Allows Administrators to manage Mailbox Storage Management activity by restricting the task to only apply to individual messages over a certain size. Setting this option to 0 (zero) will set the task to stub all messages that meet the additional criteria selected.
	Message Older Than (Days)	Allows Administrators to manage Mailbox Storage Management activity by restricting the task to only apply to messages older than a given number of days. Setting this option to 0 (zero) will set the task to stub all messages that meet the additional criteria selected.
	Enabled Mailboxes Only	The exchange allows Administrators to manage mailboxes in two 'states'; enabled or hidden. This check box ensures that the stubbing task will only be applied to those mailboxes set to 'enabled' within Exchange.
	Read Mails Only	Restricts stubbing activity to those messages that have been marked as read.
	Must-Have Attachments	Ensures that Mimecast stubs the full message body and all attachments (as opposed to the Stubbing Type of Attachments Only, which leaves the message body). This setting will not stub messages unless they have an attachment.
	Attachments Larger Than (KB)	This field is only displayed when either the Stub Message Attachment or Stub Message Attachment (Universal Access) options are selected. It ensures that only attachments over a certain size will be stubbed.
Folder Options	Include Inbox	Messages matching the criteria in the definition and found in the Inbox will be managed.
	Include Sent Items	Messages matching the criteria in the definition and found in the Deleted items will be managed.
	Include Deleted Items	Messages matching the criteria in the definition and found in the Deleted items will be managed.
	Include Junk Mail	Messages matching the criteria in the definition and found in the Junk Mail will be managed.
	Include Other Folders	Messages matching the criteria in the definition and found in folders not considered Exchange Well-Known folders will be managed.
Flagged Message Options	Up to Status Level	Allows Administrators to configure if messages should be stubbed based on whether a message has been marked or is flagged as completed.
	Include Unflagged Items	Should be selected as standard to ensure that all messages, regardless of whether a flag is present, will be considered for stubbing (considering the other criteria).
	Include Flags	All other options refer to the flag color assigned to a message. Flag color is customized within Outlook 2003 and later versions; therefore, care should be taken when selecting a single colored flag to be included. Outlook 2007 utilizes a red flag system and allows the categorization of emails via color. The Include Red Flags checkbox covers the red flags; however, the customized color categorization of messages is not.
Filter Options	Up to Security Level	Outlook allows you to assign messages a Sensitivity level, the lowest being Normal and the highest being Confidential. The filter specifies an "up to" security level. Selecting Confidential, for example, will ensure that all messages are captured, regardless of the assigned Sensitivity level.
	Up to Importance Level	Administrators can assign an Importance level against a message, from Low to High. The filter specifies an "up to" importance level; therefore, selecting High, for example, will ensure that all messages are captured, regardless of assigned Importance levels.

5. Select Save and Exit to complete the definition.

Next Step(s)

If you have not already done so, you must configure a Schedule for the Exchange Task outlined in the two articles below. 

1. Create an Exchange Task in the Administration Console. This is where you select your definition and schedule and apply it to group(s) and/or users.

2. Create a Task Schedule in the Administration Console. This is where you define when the Task Schedule runs.