Modern Attachments in eDiscovery: What Your Collection Strategy Is Probably Missing
When someone shares a file through Microsoft 365, the platform doesn’t always do what users think it does. A “modern attachment” looks like a traditional email attachment, but it’s actually a cloud link to a live document stored in OneDrive or SharePoint. The sender controls permissions, everyone accesses the same version, and edits happen in one shared location rather than across a dozen copies sitting in different inboxes.
An embedded URL is different. It’s a standard hyperlink pasted into an email or chat message that points to a file, a webpage, or an internal system. The platform doesn’t treat it as an attachment. There’s no automatic permission handling, no version control tied to the email, and no integration with the message’s metadata.
For day-to-day collaboration, the distinction between these two sharing methods barely registers. For forensic collection, it changes how you scope the job, what you actually capture, and whether the version you produce in discovery is the version that existed when the email was sent. Embedded URLs are relatively straightforward to identify and capture. Modern attachments are not. They introduce versioning complexity, linking requirements, and scoping decisions that most collection workflows were never built to handle.
This used to be an edge case. It isn’t anymore. As organizations have moved to Microsoft 365 and cloud-first collaboration, modern attachments have become the default way files are shared internally. Most users don’t even realize their “attachment” is a cloud link. That means most custodian data collected today includes modern attachments whether the legal team planned for them or not. Teams that haven’t updated their collection protocols and QC workflows to account for this are carrying risk they may not see until it surfaces during production or, worse, during a challenge to the collection itself.
Why This Matters for Forensic Collections
Modern attachments create three specific challenges during forensic collection, and each one requires decisions that traditional workflows weren’t designed to address.
1. The versioning problem
When Microsoft Purview exports a modern attachment, the default behavior is to capture the current version of the document, not the version that existed when the email was sent. Purview offers options to export the last 10, 100, or all available versions, but there is currently no native mechanism to automatically match the exact version of the file to the timestamp of the original email.
To see why this matters, consider a straightforward scenario. A custodian emails a draft contract to outside counsel on March 1. Over the next three months, the document goes through fifteen rounds of edits as terms get negotiated. When the collection happens in June, Purview captures the current June version by default. The March 1 version, the one the custodian actually shared, may still exist in the version history, but identifying it requires manual comparison of export timestamps against communication dates. If opposing counsel or a regulator asks for the document as it existed at the time of the communication, your team needs a defensible process for identifying the closest available version, and a clear explanation for why the current version was produced if that process falls short.
2. The linking challenge
Recent Microsoft Purview feature releases have made it easier to link modern attachments back to their parent emails during collection. But easier does not mean automatic, and the decision about whether to link isn’t always straightforward. Not every matter, legal team, or internal investigation will require modern attachments to be linked to the emails that shared them. The decision depends on scope, proportionality, and the specific questions the investigation needs to answer.
The key is making that call early, during collection scoping, before the work begins. When forensic teams defer the linking decision and it surfaces as a gap mid-review, the consequences compound. The team has to go back to the collection source, re-export with linking enabled, re-process the data, and then reconcile what has already been reviewed against the updated dataset. Depending on the volume, that can add days or weeks to the timeline. It also raises questions about process consistency that no legal team wants to answer if the collection is challenged. A reviewer who saw a modern attachment as a standalone document in round one and then sees it linked to its parent email in round two is working with a different evidentiary picture, and that inconsistency needs to be documented and explained.
3. The case law gap
Courts across jurisdictions are not aligned on how to treat modern attachments in discovery. Some treat them as functionally equivalent to traditional attachments and expect full production. Others evaluate them on a case-by-case basis, weighing proportionality and burden against the evidentiary value of capturing every available version. ESI protocols that were drafted before modern attachments became the default sharing method in Microsoft 365 environments may not address these questions at all.
This is an area where the law is still catching up to the technology. Legal teams that wait for clear, uniform precedent before updating their protocols are taking on avoidable risk. The safer approach is to address modern attachments proactively in your ESI agreements: specify how they’ll be identified during collection, define what version history will be preserved, and establish how linked files will be produced alongside their parent communications. Having that language in place before a dispute arises gives your team a defensible framework regardless of how the case law develops.
Practical Steps for Legal Teams
Update your ESI protocols. If your current ESI protocols don’t address modern attachments specifically, they have a gap. At minimum, your protocols should define how modern attachments will be identified during collection, what version history will be preserved, and whether linked files will be collected alongside their parent communications. If you’re negotiating an ESI agreement right now and modern attachments aren’t addressed, raise it before the agreement is signed.
Scope the linking decision during collection planning. Decide early whether modern attachments need to be linked to their parent emails for this specific matter. This decision affects collection scope, review volume, and cost. Making it during planning takes five minutes. Making it after review has started takes weeks of rework.
Account for versioning in your QC process. If the matter requires point-in-time accuracy, build a verification step into your quality control workflow. Compare export timestamps against communication dates and flag discrepancies before production, not after opposing counsel raises them.
Work with a forensic team that understands cloud collection. Modern attachments are one of many areas where Microsoft 365 collections have become more complex than the tools and processes most legal teams built for on-premises environments. Lineal’s forensic collections team handles Microsoft 365 collections daily, including modern attachment linking, version history management, and defensible ESI protocol development. When a collection is challenged, these are the details that determine whether it holds up.
Talk to Lineal about how modern attachments should be handled in your next collection.
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About Author
Laura Collins is an accomplished digital forensics examiner, currently serving as Vice President of Shared Services & Forensics at Lineal. With extensive experience overseeing global forensic operations, complex investigations, and eDiscovery delivery, she has built her career across corporate, legal, and incident‑response environments. Laura’s background spans hands‑on forensic analysis, major incident response, and leading high‑performing teams to deliver innovative, defensible solutions for clients worldwide. Recognised for her operational leadership and deep technical expertise, she is committed to advancing high‑quality forensic services while driving collaboration, efficiency, and excellence across the organisation.
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About Lineal
Lineal is an innovative eDiscovery and legal technology solutions company that empowers law firms and corporations with modern data management and review strategies. Established in 2009, Lineal specializes in comprehensive eDiscovery services, leveraging its proprietary technology suite, Amplify™ to enhance efficiency and accuracy in handling large volumes of electronic data. With a global presence and a team of experienced professionals, Lineal is dedicated to delivering custom-tailored solutions that drive optimal legal outcomes for its clients. For more information, visit lineal.com