Microsoft Exchange Definitions

If you’ve ever gotten a little lost diving into Microsoft Exchange docs, you’re not alone. Untangle the core terminology here.

Microsoft Exchange Definitions

If you’ve ever gotten a little lost diving into Microsoft Exchange docs, you’re not alone (that’s why we built Nylas, to help make integrating with Exchange accounts a breeze). 

Given its long history, Exchange has countless additions and qualifications to keep track of within the infrastructure of the Exchange family. You might be creating a plan of action with assumptions about how certain components of Exchange work only to discover unexpected twists and turns that leave you wondering where you are amongst the Microsoft product ecosystem.

To aid you as you embark on your Exchange journey, we’ve put together an Exchange encyclopedia with terms and definitions to help guide you. Let’s first get a big-picture view of broader Exchange and Microsoft products.

Microsoft has unified all of their Exchange documentation at the official Microsoft Docs site. You may occasionally encounter references to the legacy portal TechNet, which once contained general documentation for Exchange, or the Microsoft Developer Network (MSDN) which has since been transformed into the landing page at

Here are the important terms to know for the Microsoft Exchange product ecosystem.

  • Microsoft Exchange – The umbrella term that covers all Exchange products and services Microsoft offers. Within this, there are two primary forms of Exchange: Exchange Online and Exchange Server.
  • Exchange Online – Microsoft’s cloud-hosted Exchange server. Exchange Online is offered as part of Office 365. It is possible to purchase Exchange Online with or without other services like OneDrive, Skype, Yammer, or applications like Word, Excel, and Outlook. Exchange Online provides users a view of their email via a web-based Outlook client. Take a look at the plans & pricing to learn more about the services Microsoft offers.
  • Exchange Server – The downloadable software to run Exchange yourself on prem. It only runs on Windows Server machines, and the Windows Server version is tightly connected to the Exchange Server version. Versions have both a year and a version number; take a look at the list of Exchange Server versions to learn more.
  • Windows Server – The operating system required to run Exchange Server. It also comes pre-integrated with Active Directory.
  • Office 365 – A general suite of cloud-hosted Microsoft products that includes Exchange Online  among other products.
  • Active Directory (AD) – Microsoft’s Directory Server that provides authentication and authorization. It uses LDAP (rfc4510) to manage objects like users, computers, and groups. The most commonly used objects are users, computers, and groups. Active Directory is tightly integrated with Exchange Server and Windows Server
  • Azure Active Directory – An Active Directory service hosted on Microsoft’s Azure cloud platform. It’s frequently used for OAuth.

If you’re looking to build an app that integrates Exchange accounts, our guide on how to use Exchange Web Services to authenticate user accounts.

Exchange Web Services (EWS) 

Exchange Web Services is a protocol designed to enable developers to integrate data and functionality from Exchange into their app. EWS is the best option for developing feature-rich client and server applications because it exposes many properties that aren’t available with EAS.

Here are a few key terms you should know:

  • Exchange Web Services (EWS) – A generic term that refers to SOAP data APIs that are used to access Exchange installations, for both on-prem Exchange and Exchange Online.
  • EWS Managed API – The name Microsoft uses for the C# client library that wraps the EWS SOAP APIs
  • Service Accounts – An umbrella term to let you use a single access token to access many mailboxes in a company’s account. Exchange Web Services calls this “Impersonation”. Exchange Online via the Graph API calls these “Application Accounts.”
  • Impersonation – Enables a Service Application to impersonate a User Account.

To learn more about all of this, take a look at Microsoft’s guide to get started with EWS client applications, or you can head over to the reference documentation for a deeper dive.

Exchange Active Sync (EAS) 

Exchange ActiveSync was introduced in 2003 as a proprietary binary protocol that was designed specifically to sync Exchange with mobile clients. It introduced a lightweight, idempotent procedure for data synchronization and was ideal for when working with high-latency, low-bandwidth connections, such as messaging applications that run on mobile devices. 

Since EAS was designed to sync mobile, at minimum, you need to understand the different responses to the Sync command, and common status codes. You should also read through the Exchange Server protocol documentation to get a lay of the land before writing any code. 

There is really only one key term you need to know for EAS:

  • Device – Since EAS was designed to sync to mobile devices, the “Device” is the top-level sync client you will want to use to manage the sync process.

Not sure if you need EAS or EWS? Read Microsoft’s guide to help make the decision.

Nylas Offers an Easier Way to Integrate with Microsoft Exchange 

The Nylas Communications Platform integrates with 100% of email, calendar, and contacts providers, including Exchange, Office365, and Outlook. With Nylas, you can build a full email, calendar, and contacts integration in a fraction of the time it would take to build a direct integration with Exchange.

Nylas Hosted Auth is the quickest and easiest way to setup user authentication for your app. Simply redirect users to a Nylas login page and we’ll handle the rest including auto-detection of third party providers and managing token exchanges with providers like Microsoft.

Illustration of the Nylas Hosted Auth service that integrates with 100% of email, calendar, and contacts providers, including Google

Head over to the Nylas docs to learn more about Nylas Hosted Auth

Building an integration with Exchange can be a big commitment in terms of time and money. Our ROI calculator computes that building a direct integration with Exchange on your own would take around 19,642 hours. With Nylas, it would take one developer as little as 18 days to build a full email, calendar, and contacts integration. If you’d like to try out the Nylas Communication Platform, create a free developer account and start building your integration today.

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