Proofpoint Enterprise Archive: Email Attachment Stubbing

Email attachment stubbing allows you to manage email mailbox sizes by removing email storage-intensive attachments from Exchange while keeping those email attachments accessible to users.

With Proofpoint Enterprise Archive email attachment stubbing, you reduce the amount of email storage required within Exchange by leveraging the data already stored in the email storage archive. Users have continued access to their email messages from Outlook within their folder structure. Users also benefit from virtually unlimited email mailboxes because the automated process helps them stay within their mailbox quotas. With email attachments making up the bulk of the data stored on the Exchange server, email attachment stubbing means less email storage data within Exchange for a faster, more reliable email messaging system - without end user compromises.

Proofpoint's email attachment stubbing is an automated process that replaces email attachments (which are stored in Exchange) with a much smaller "stub" that points to the copy of the email attachment that is stored in Proofpoint Enterprise Archive.

The email attachment stubbing process takes place on a regular basis (the frequency and exact time is configurable), automatically checking mailboxes and replacing email attachments with stubs. The mailboxes this service checks, and the rules it uses to determine what email attachments to stub, are defined in a stubbing policy. Unlike email archiving, which happens as soon as a message is sent or received, email attachment stubbing occurs at a point in the future (for example, 30 days after a message is sent or received).

The Proofpoint user interface lets customers define email attachment stubbing policies that determine which email messages are stubbed. You can set policies to replace attachments with a pointer to the archive based on the size of the attachment and/or the age of the attachment. Separate thresholds can be set for the inbox, sent items, deleted items, and the remaining folders. In addition, customers can configure the email storage management solution to stub attachments more aggressively if a user is approaching their Exchange mailbox quota.

Yes. Each stubbing policy is configured to work for a set of users or Active Directory groups. You can create as many stubbing policies as you want, allowing you to treat messages differently for each group of users.

The stubbing process is designed to minimize the impact on Exchange by running during off-peak hours. Customers have complete flexibility to define stubbing windows to avoid periods of heavy user activity and backup/maintenance periods. Different stubbing windows can be defined based upon time of day and day of week – allowing you to do the majority of processing on the weekend, if desired.

Proofpoint's unique approach to stubbing works by inspecting user mailboxes, identifying email messages that match a stubbing policy and trying to find the corresponding message that is already in the email storage archive. Messages generally get into the email storage archive through the journal-based archiving process or through an import of historical data. If the system can't find the corresponding message in the email storage archive, it can optionally store a copy of the attachments in the archive so that they can be stubbed. Note that if you intend to import historical data into the email storage archive you should wait until this is completed before enabling this option to avoid duplicate data.

No. Proofpoint Enterprise Archive does not build indexes for attachments that are stored solely for the purpose of historical attachment stubbing. If you want to be able to search through historical mail, and get the benefit of stubbing this content, you should import historical mail. The standard stubbing process will then find these messages and be able to stub the attachments.

Customers can define specific stubbing retention policies for each group of mailboxes. If a stubbing retention policy isn't defined for a given mailbox, the default retention policy is assigned.

When a message is stubbed, the message remains in the user's mailbox in its original folder. The attachments in these messages are replaced with a small HTML file that has a link to the attachment in the archive. Users can open the stubbed attachment by clicking on the HTML file, then clicking on the "retrieve attachment from the archive" link. Users can save attachments by right-clicking on this link.

To allow users to retrieve stubbed attachments from the email storage archive when they are outside of the office, Proofpoint provides a special HTTP proxy to provide access to the email storage appliance. This email storage archive proxy is installed on the customer's Outlook Web Access server, allowing leverage of existing digital certificates and DNS entries. With the email storage archive proxy in place, stubs point to the proxy, which in turn provides access to any appliances and allowing users to access stubbed attachments when they are outside the corporate network.

Yes. Users see their messages as normal in Outlook and click on the stubbed attachment to retrieve it from the archive.

Yes. Users see their messages as normal in OWA, and click stubbed attachment to retrieve it from the email storage archive. Seamless access within OWA is provided in conjunction with the Archive Proxy installed on the OWA servers.

Yes. Any email client that can open an HTML-format file attachment in a browser and allow the user to follow a link to retrieve a binary file can be used to access a stubbed attachment. As a result, all desktop email clients or mobile devices such as Blackberry, iPhone and Windows Mobile devices can access stubbed attachments.

Client software is not required to process or access stubbed messages. Proofpoint is developing an optional client-side software component that caches stubbed attachments locally, allowing end users to access stubbed attachments when they are disconnected from the network.

If you wish to provide remote access to stubs, you must install the archive proxy on your front-end servers that provide OWA services. You do not need to install any software on the backend servers.

Replacing an attachment with a pointer to the email storage archive dramatically reduces the amount of email storage space within the Exchange database that a message occupies. However, the Exchange database itself does not shrink in size until an offline defragmentation is performed. Even without defragmentation, most Exchange backup processes take advantage of the empty email storage space in the database, allowing for faster backups.

Proofpoint replaces attachments with pointers to the email storage archive, but leaves the message body intact. Attachments can represent up to 90% of the email storage space and are accessed far less frequently than the message bodies. As such, Proofpoint's attachment stubbing provides the key email storage management benefits while minimizing the impact on end users.