Office 365 eDiscovery E-Mail Search Limitations

Office 365 eDiscovery Email

Office 365 eDiscovery EmailOffice 365 is enjoying continued success – driven partly by the popularity of Microsoft Outlook.  Outlook, according to the Radicati Group, is the most popular business email client on the market, with a 60% market share just a couple of years ago. For years to come, Office 365 will be used by companies to conduct the electronic discovery of e-mail.

Given the significance of Office 365, what are Office 365’s e-mail search limitations from a discovery perspective?  What do users need to be aware of when conducting litigation, internal investigations and regulatory compliance?

The eDiscovery cases page in the Office 365 Compliance Center is where cases are accessed and managed.  Here, users can identify relevant e-mail and place litigation holds on sources such as SharePoint and Exchange (Exchange is the Office 356 mail store).  Holds can be placed based on key word queries, dates, authors, senders, and e-mail domains.

When searching for keywords, standard Boolean (AND, OR, NOT) and proximity operators (NEAR(n)) can be used, as well as wildcards that expand keywords to include terms that contain part of a keyword or terms that have alternative spellings.

From what we can tell, Office 365 is still using the FAST search engine and Continuous Crawl which insures that new items are almost instantly searchable.


There are clear e-mail search limitations in Office 365 to be aware of when conducting eDiscovery.

  • OCR.  Because OCR is not being performed by Office 365, image-based files will not be searched (if OCR is added at some point – which is unlikely – check with Microsoft Support on the OCR engine.  Not all OCR engines support the recognition of Chinese, Japanese and other foreign languages).

  • Password-Protected Attachments.  Password-protected e-mail attachments are not searched.

  • Indexing of Special Characters.  Special characters (e.g., those often found in patent cases, such as “, . / – ‘ _ &”) are not indexed, which can result in a higher number of documents in the attorney review stage of the eDiscovery process.


Understanding its limitations, should Office 365 be used for eDiscovery search?  If so, to what extent?  As a testifying eDiscovery expert, I have firsthand experience in cases in which companies performed electronic discovery using the basic features such as those offered by Office 365.  When evidence is missed, the consequences can be very severe.

The key is properly weighing these proportionality factors from the soon-to-be-updated Federal Rules of Civil Procedure (Rule 26(b)(2)(C)(iii):

  • the needs of the case

  • the amount in controversy

  • the parties’ resources

  • the importance of the issues at stake in the action, and

  • the importance of the discovery in resolving the issues.

Consider leveraging the Proportionality Triangle (read more about the Proportionality Triangle here) as you consider your eDiscovery process for a given case.


Office 365 offers a significant amount of utility with regards to litigation holds and preservation.  However, it’s e-mail search capabilities have distinct limitations.  Consider these limitations as you determine the shape of your eDiscovery process.

Founder & Principal Consultant
Quantum E-Discovery

Jeff believes in saving time and money in e-discovery by applying a variety of analytics tools early in a case, well before moving content to expensive final review platforms. Over the past 20+ years he has accumulated a variety of tools that can be applied as needed in specific situations. Learn about Jeff’s e-discovery philosophy here.