Mailbox Storage Management

Document created by user.oxriBaJeN4 Employee on Sep 11, 2015Last modified by user.oxriBaJeN4 Employee on Jun 21, 2019
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The Mailbox Storage Management feature uses native Exchange entry points, to identify and take action on admin or user defined email messages / email attachments from Exchange mailboxes. This helps manage Exchange storage, and leverages the Mimecast archive directly from the Exchange mailbox.

Mailbox Storage Management can be defined to take one of the following storage management actions:


ActionMimecast for Outlook RequiredDescription
Message Delete


The full message including attachments is completely deleted from the Exchange Mailbox.

Full Message Stub

YesThe message body and attachment components are removed from the message, leaving behind a small message skeleton linking to the Mimecast archive.

Attachment Stub


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)


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).



Mailbox Storage Management enables Administrators to control the size of mailboxes on the corporate Exchange server, with the option to not impact the original location of managed email. As the size of attachments being sent via email continues to grow, and with email being the choice means of communication for many businesses, Administrators are constantly faced with the challenge of managing local resources and ensuring there is sufficient storage in their Exchange environment.


Using Mailbox Storage Management, data found to be in the Mimecast archive can be removed from the Exchange mailbox safely with end-user productivity options such as:

  • Replacing message components with links to the Mimecast archive while leaving the message in it's original location,
  • Deleting messages and using the Archive Folders feature in Mimecast applications to view the message in it's original location (Mailbox Folder Replication required).




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

  • Exchange Mailbox Search: Full message stub removes the message body from the Exchange mailbox, consequently users will no longer be able to use native Exchange client, for example, Microsoft Outlook, search tools to search for terms they expect to be in the body of a "stubbed" message. This isn't an issue for attachment stubbing.
  • Client Requirements: Full message and attachment stubs require that the end user uses the Mimecast for Outlook software and a Mimecast supported version Microsoft Outlook for Windows to retrieve the stubbed data. This isn't an issue for the Universal Access Attachment Stubbing feature.


See Also...