Managing Blocked / Stripped and Linked Attachments

Document created by user.oxriBaJeN4 Employee on Sep 11, 2015Last modified by user.oxriBaJeN4 Employee on Apr 2, 2019
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This guide provides an overview of what happens if an attachment is blocked, or striped and linked, by one of the following policies:

Attachment ManagementAllows individual attachment types to be blocked, linked or held using an attachment set.
Attachment Block on SizeRemoves attachments based on the cumulative size of the attachments.
Attachment Hold on SizeHolds the email based on the cumulative size of the attachments.
Attachment Link on SizeStrips and Links all attachments based on the cumulative size of the attachments.
For attachments held by Targeted Threat Protection - Attachment Protect, see the Targeted Threat Protection - Attachment Protect page.

Any attachment that is blocked or stripped and linked from a message based on an attachment policy, is logged and available for release by an administrator using stripped attachments. Attachment policies are based on mail flow, and can be applied to both inbound or outbound mail. Blocked or stripped and linked attachments are available in the archive until the message's expiry date. See the Retention Adjustments page for full details.


When an attachment is blocked or stripped and linked, the internal end user is notified. Administrators can review and release either the:

  • Attachment which will be delivered with a system notification.
  • Original message which is delivered to the recipient.




Consider the following when configuring any of the following policies:

  • If you've the Targeted Threat Protection - Attachment Protect product on your Mimecast account, you can release attachments to the sandbox.
  • You can limit messages based on the total size of the message, including all attachments. The policies listed above only affect individual attachments.


Viewing Messages with Stripped Attachments

Messages with stripped attachments sent by Large File Send can be tracked using a separate viewer. See the "Large File Send Attachments" section below for full details.

To view attachments that have been removed from messages:

  • Log on to the Administration Console.
  • Click on the Administration toolbar menu item.
  • Select the Monitoring | Attachments menu item. The following information regarding the message and its attachments is displayed:
    Attempt FromDisplays the sender's email address.
    Deliver ToDisplays the recipient's email address.
    File NameDisplays the blocked or stripped and linked attachment file name.
    ExtDisplays the blocked or stripped and linked attachment file extension. This refers to the actual MIME type of the attachment, so if the file type has been renamed, the actual file type is displayed.

    Displays the blocked or stripped and linked attachment size.

    Date TimeDisplays the message's date and time.
    StatusDisplays an icon indicating the attachment's status:
    IconAttachment StatusDescription
    Attachment LinkedThe attachment has been removed from the message as a result of a strip and link action. This could because of an Attachment Link on Size policy, or by selecting the link option in an Attachment Set. The end user receives the original message with a system notification attachment. A HTTPS hyperlink is provided for the end user to download the attachment directly from Mimecast.
    Attachment_released.gifAttachment ReleasedThe attachment, or the original message with an attachment, has been released by an administrator to the end user.
    Blocked_Attachment.gifAttachment BlockedThe attachment has been blocked by an Attachment Management or Attachment Block on Size policy.
Use the search field to filter the view. You can search for the from / to address or filename. By default, stripped attachments display one month's worth of attachments. You can also change the date range by using the "From" and "To" calendar controls.

Message InformationAdditional information is provided when a message is selected, including the message status and the details of the attachment. The "Released" field indicates if the attachment has been released by an administrator. It is only displayed for messages with attachments blocked by an

  • Attachment Block on Size policy.
  • Attachment Management policy with the "Deny" option enabled.


Releasing Messages and Attachments


To release an attachment:

  1. Log on to the Administration Console.
  2. Click on the Administration toolbar button.
  3. Select the Monitoring | Attachments menu item.
  4. Right-click on the message. A popup menu is displayed.
  5. Select one of the following options:
    Release Original MessageReleases the original message with attachment to the end user, which maintains the context of the attachment.
    Release AttachmentReleases the attachment via a system notification to the end user.
    View Attachment DetailDisplays the stripped attachment review page as displayed above.
    View Email DataDisplays the contents of the message, and allows you to preview the attachment prior to releasing to the end user.
    You can select multiple attachments to be released by using the check box next to each item, and selecting the Release Attachment button on the top toolbar.

Released Attachments Log


When an item is released from stripped attachments, an entry is listed in the Released Attachments Log. To view the log:

  1. Log on to the Administration Console.
  2. Click on the Administration toolbar button.
  3. Select the Monitoring | Attachments menu item.
  4. Click on the View | Release Log menu option. The release log is displayed for the last month by default, and provides the following information:
    Released ByDisplays the email address of the user who released the attachment. This can be an end user if the attachment was released via a digest, or the administrator.

    Attachment Name

    The full file name of the attachment.
    Released ToThe email address to which the attachment was delivered.
    MethodSpecifies how the attachment was released. The possible values are "Self Release" if the attachment was released via a digest, or "Administration Console" if released by an administrator.
    TypeDisplays if it was the original message or attachment that was released.
    Date TimeDisplays the time and date that the message was released.
    You can customize the Attachment Block and Attachment Release notifications. For more information, refer to the Configuring Notification Sets Definitions and Policies page.

Large File Send Attachments


Large File Send services can be enabled through Mimecast for Outlook and Mimecast for Mac when composing new messages, or by Attachment Management policies. Large File Send attachments are not transmitted through the company email server, but are instead sent directly through Mimecast. This helps to reduce the load on the server and user application.

Large File Send attachments can be released from this viewer by those with content viewing rights.

Users can monitor the Large File Send files from the Mimecast ribbon in Mimecast for Outlook or from the Large File Send manager in Mimecast for Mac. Administrators can monitor these files from the Administration Console:

  1. Log on to the Administration Console.
  2. Click on the Administration toolbar button.
  3. Select the Monitoring | Attachments menu item.
  4. Click on the Large File Send Attachments button.
  5. Select a file to view more details on the file, including the email receipt / delivery details.


See Also...


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