Email stubbing sounds like a smart trade-off: move data out of your mailbox, keep a pointer in its place, and free up server space without disrupting the user experience. Clean, simple, efficient.
The problem is that it rarely works out that way.
Despite being widely adopted in the early days of email archiving, stubbing has a well-documented track record of creating more problems than it solves, from Exchange performance issues to ediscovery nightmares.
Many archiving vendors have quietly moved away from it. Others still rely on it.
In this article, we’ll cover:
- What email stubbing is and how it works
- Why it was so widely adopted as a storage reduction strategy
- Five reasons why stubbing is a flawed approach to email archiving
- Why Jatheon never relied on stubbing, and what we do instead
What Is Email Stubbing?
Email archiving solves the compliance and retention problem, but it introduces another one.
Every email that gets captured still has to live somewhere, and for organizations running on-premises Exchange environments, keeping that data on primary storage was expensive. Mailboxes fill up fast, attachments compound the problem, and the more data sitting on primary storage, the heavier the load on the Exchange server.
Email stubbing was the industry’s answer to that tension. Rather than storing everything on the primary server, stubbing moves email data to cheaper secondary storage and leaves a lightweight placeholder, or a “stub” in the original mailbox. The stub serves as a pointer back to the full message in the archive.
Stubbing is rooted in Hierarchical Storage Management (HSM), the practice of automatically moving data between high-cost and low-cost storage tiers based on how frequently it’s accessed.
The logic was straightforward: if an email hasn’t been opened in months, why keep it on expensive primary storage? Move it somewhere cheaper and leave a pointer behind.
When a user opens a stubbed email, driver software intercepts the request and retrieves the full message from the archive in real time. In theory, the experience is seamless. In practice, it rarely is.
There are two types of stubbing in email archiving:
- Attachment stubbing — only the attachment data is removed from the server and replaced with a link. The message body remains in the mailbox.
- Entire message stubbing — the full message body is replaced by a short text excerpt containing a link back to the original in the archive.
Why Did Organizations Turn to Stubbing
For organizations in regulated industries, email archiving isn’t optional. Depending on the sector, federal and industry regulations require email to be retained for anywhere from three to ten years or more. The volume of data that needs to be stored, indexed, and kept retrievable adds up fast.
But compliance isn’t the only pressure IT teams face.
For organizations running on-premises Exchange environments, storing that data without overwhelming the primary server used to be a persistent operational headache. Every attachment, every thread, every forwarded chain competed for space on expensive server infrastructure. That’s the gap stubbing was designed to fill.
By offloading older, less-accessed email data to cheaper secondary storage and keeping a lightweight placeholder in the mailbox, IT teams could keep primary storage lean without forcing users to change their workflows.
Outlook looked exactly the same. The folder structure was intact. Every message appeared right where the user originally filed it.
For organizations managing thousands of mailboxes, the combination of real storage savings, and zero workflow disruption looked like a compelling proposition. Stubbing became standard practice across much of the archiving industry through the 2000s and into the 2010s.
The trouble is that “practical” and “reliable” turned out to be two very different things, especially when compliance obligations, legal discovery, and long-term data integrity were at stake.
The Problem With Email Stubbing: 5 Reasons to Avoid It
1. Stubbing doesn’t improve server performance
Email stubbing is often sold as a way to lighten the load on your email server. The reality is more complicated, and for most organizations, the performance gains never materialize the way they’re supposed to.
Here’s why. When a user opens a stubbed email, the server has to pull data from two separate locations: the stub in the live mailbox and the full message in the archive. Every single request triggers that dual retrieval process. At scale, across thousands of mailboxes, that adds complexity and latency rather than reducing it.
More importantly, Exchange server performance is driven primarily by the number of items in a mailbox, not their size.
Stubbing reduces mailbox size, but it doesn’t reduce item count, as every stub still registers as an item. A folder containing 2,000 full emails and a folder containing 2,000 stubs will perform roughly the same.
While the storage savings are real, the performance improvement largely isn’t.
For organizations that have migrated to Microsoft 365, this argument becomes even more clear-cut. Cloud storage costs have dropped dramatically, and M365 comes with its own native archiving and retention tools.
The storage problem that stubbing was designed to solve is largely a non-issue in modern cloud email environments, which makes stubbing’s performance trade-offs even harder to justify.
2. Stubs can’t be recreated
Stubbing offloads data to secondary storage, but it doesn’t eliminate the dependency on the live mail server. Every stub still occupies space as an object in Exchange, and as mailboxes grow, so does the overhead. You’re not really lightening the server’s load. Instead of that, you’re practically fragmenting your data across two locations and hoping nothing goes wrong in either one.
The bigger risk is data loss. If the archive suffers corruption, a system failure, or an incomplete migration, the stubs left behind in the mailbox become orphaned pointers to data that no longer exists. And unlike full email messages, stubs can’t be recreated.
Once that connection is broken, the data is simply gone.
This risk becomes especially acute during Microsoft 365 migrations, which are now one of the most common infrastructure projects organizations undertake. Legacy stubs frequently fail to migrate cleanly, so forwarded stubs go missing, public folders containing stubs are difficult to size correctly, and users end up opening emails post-migration and finding nothing there.
What looked like a storage solution becomes a data integrity problem at exactly the moment you can least afford it.
Marko Dinic, Jatheon’s CEO, explains why this was a line the company never crossed:
“Stubbing still takes up resources in the Exchange server. You’re basically offloading storage, but keeping the objects. This causes tremendous issues in Exchange as the number of items grow even though they seem empty. If there’s any data corruption or loss, there’s no way you can recreate stubs. The arguments against are simply too strong. At Jatheon, it was a decision that was made early on. We needed to think beyond stubbing. We needed to think smarter and more long-term.”
3. The implementation is risky
Stubbing isn’t a passive process. It requires massive changes to your Exchange server configuration and the deployment of software that sits below Outlook, intercepting every request to retrieve stubbed content from the archive.
That software needs to stay in sync with every Outlook update, every Exchange patch, and every change to the archiving solution itself. Any gap in that chain and users start hitting dead ends, which leads to emails that appear to be there but return nothing when opened.
This isn’t just a theoretical risk. Stub-dependent archiving solutions have a documented history of breaking when routine Exchange updates are applied, leaving users unable to access archived content until the vendor issues a patch. For compliance-driven organizations where continuous access to archived communications isn’t optional, that kind of dependency is an unacceptable vulnerability.
For organizations still running on-premises Exchange, that maintenance burden alone is a compelling reason to look elsewhere.
But the more pressing risk today is what happens when organizations migrate to Microsoft 365, which is now one of the most common infrastructure projects in IT.
Legacy stubs frequently don’t survive the move intact, while forwarded stubs fail to migrate. Public folders containing stubs are difficult to size correctly. And because stubs look exactly like regular emails to the migration tool, they can be silently skipped or corrupted without any immediate indication that data has been lost.
The result is users opening emails post-migration to find nothing there, or worse, discovering gaps in their archive during an ediscovery request, when the stakes are highest, and there’s no time to investigate missing data.
4. It creates complexity for end users
Stubbing promises a seamless user experience, and on the surface, it delivers one. Outlook looks exactly the same, and the folder structure is intact. Every email appears to be right where it was originally filed. For the average user, nothing seems to have changed.
The problem becomes apparent the moment they run a search.
Because stubbed content lives outside the primary mailbox, standard Outlook search returns incomplete results. Users searching for an email or attachment that has been stubbed out won’t find it through the normal search interface. They need to know to look in the archive separately, assuming they even have direct access to it.
For most end users, that distinction isn’t obvious, and the assumption is simply that the email doesn’t exist.
This problem is compounded in Microsoft 365 environments.
M365’s native search and compliance tools, including Microsoft Purview, are designed to work with data that lives within the M365 ecosystem.
Legacy stub-based archives sit outside that ecosystem entirely, which means they don’t integrate cleanly with M365 search, ediscovery workflows, or compliance reporting. IT and compliance teams end up managing two parallel systems that don’t talk to each other, which increases both complexity and the risk of something falling through the cracks.
For organizations that have moved to M365 expecting a unified, streamlined compliance environment, discovering that their legacy archive requires a separate interface, separate search, and separate ediscovery workflow is a significant and often unexpected operational burden.
5. Stubs can create legal risks
Of all the reasons to avoid stubbing, the legal risk is the most consequential and the most underappreciated.
When a user interacts with a stub, those interactions generate metadata. Flagging an email, moving it to a different folder, marking it as read, assigning a retention category, or deleting it. All these actions leave a trail attached to the stub itself, separate from the original message sitting in the archive.
That metadata can be directly relevant in litigation. And because it lives on the stub in the live mail system rather than in the archive, it’s easy to overlook, mishandle, or lose entirely.
This creates a gap at the worst possible moment.
The ediscovery process typically begins with an archive-wide search, which is then exported for further processing. The problem is that this search operates on the archive and skips the stubs sitting in the live mail system entirely.
Any metadata generated by user interactions with those stubs doesn’t make it into the export. Evidence that should have been produced wasn’t, often without anyone realizing it.
The legal exposure doesn’t stop there. Because stubs look identical to regular emails from the user’s perspective, they can be manipulated, moved, deleted, or altered in ways that aren’t immediately visible to compliance or legal teams.
That trail of actions needs to be documented and preserved. Pulling a message from the archive without reconnecting it to its stub in a legally defensible way can be characterized as spoliation of evidence and falls short of full disclosure requirements.
In regulated industries, that risk doesn’t stay theoretical for long. It surfaces the moment a legal request hits a mailbox full of stubs.
Is Email Stubbing Still Used Today?
Stubbing hasn’t disappeared entirely, but it’s a dying practice.
Most modern archiving vendors have moved away from it, and the shift to cloud-based email has made it increasingly impractical. Microsoft 365’s native retention and compliance tools have replaced much of what stubbing was originally designed to do, and at a fraction of the operational complexity.
Still, some archiving vendors still rely on email stubbing to manage storage, particularly in on-prem environments where older infrastructure hasn’t been modernized. Organizations that have been with the same archiving provider for a long time may be running on a stubbing-dependent system without fully realizing the risks it carries.
If you’re evaluating an archiving solution or auditing the one you already have, it’s worth asking directly if stubbing is involved. The answer matters more than most vendors will volunteer.
What to Use Instead of Email Stubbing
The good news is that the problems stubbing was designed to solve, and that is keeping primary storage lean without disrupting user access, are solved problems in modern archiving.
Today’s purpose-built archiving solutions capture email in full at the point of delivery and store it in a separate, tamper-proof repository without touching the live mail server at all. There are no stubs, no split data locations, and no driver software to maintain.
The archive is entirely independent of the mail server, which means Exchange updates, M365 migrations, and infrastructure changes don’t put archived data at risk.
From the end user’s perspective, access is straightforward: a single search interface covers the full archive without the incomplete results that stub-based systems produce.
For compliance and legal teams, every message is stored in its entirety with full metadata intact, making ediscovery exports clean, complete, and legally defensible from the start.
Storage is handled through purpose-built data management rather than fragile pointers.
Retention policies automatically manage what gets kept and for how long, without any dependency on the live mailbox. When data needs to be produced for a legal request or a regulatory audit, it’s all in one place, in one system, with a complete and unbroken chain of custody.
Jatheon has never relied on stubbing. From the beginning, the decision was to build an archiving solution that doesn’t create new problems while solving the existing ones. That’s why our platform works with your infrastructure rather than around it.
Summary of the Main Points
- Email stubbing was designed to reduce primary storage costs by replacing emails with lightweight pointers, but the operational and legal problems it creates far outweigh the storage savings.
- Stubbing reduces mailbox size but doesn’t reduce item count, which means the server performance gains organizations expected rarely materialized.
- If the archive suffers data loss or corruption, stubs become orphaned pointers with no way to recover what they were pointing to.
- Every Outlook update, Exchange patch, or infrastructure change is a potential point of failure for a stub-dependent system.
- Users searching for emails in Outlook get incomplete results without knowing why, and in M365 environments, stub-based archives don’t integrate with native compliance and ediscovery tools.
- Stubs generate their own metadata through user interactions that standard archive searches don’t capture, creating gaps in evidence production that can rise to the level of spoliation.
- The shift to cloud email has largely eliminated the storage problem that stubbing was built to solve, which makes its risks even harder to justify today.
- Some legacy vendors still rely on stubbing. So, if you’re evaluating or auditing an archiving solution, it’s worth asking directly whether it’s involved.
If your organization is running a stub-dependent archiving solution, we’d be happy to show you a better way. Contact us at sales@jatheon.com or book a demo to see how Jatheon handles archiving without the complexity, risk, and data integrity problems that stubbing creates.
FAQ
What is the difference between email archiving and email stubbing?
Email archiving captures and stores email in full in a separate, tamper-proof repository. Stubbing is a storage-management technique that removes email data from the live server and replaces it with a pointer. Archiving is the goal, while stubbing is one approach to managing the storage it requires.
Does stubbing affect ediscovery?
Yes, significantly. Archive-wide ediscovery searches skip stubs entirely, meaning metadata generated by user interactions with stubbed emails can be missed. Failing to produce that data in a legally defensible manner can constitute spoliation of evidence, a serious legal liability for any organization in litigation.
Is email stubbing still used in Microsoft 365?
Stubbing is largely incompatible with modern M365 environments. Microsoft 365 has its own native retention and compliance tools, and legacy stub-based archives don’t integrate cleanly with them. Organizations migrating to M365 with stub-dependent archives frequently encounter broken stubs, missing data, and incomplete ediscovery workflows.
Can stubbed emails be recovered if data is lost?
No. If the archive suffers data loss or corruption, stubs become orphaned pointers with nothing to retrieve. Unlike full email messages, stubs cannot be recreated. This makes stubbing a serious data integrity risk, particularly during infrastructure changes or migrations.
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