What Is EWS? Exchange Web Services and Its Retirement

Exchange Web Services (EWS) is one of the oldest ways an application can talk to a Microsoft mailbox, and it is on its way out. If you landed here because an integration warned you about EWS, or because Microsoft's admin center keeps nudging you, the short version is this: EWS still works today, but Microsoft is switching it off in Exchange Online on a published, phased schedule.

This page explains what EWS is, how it works, when it stops working, and what to use instead.

What is Exchange Web Services (EWS)?#

Exchange Web Services (EWS) is a SOAP-based API that Microsoft introduced with Exchange Server 2007. It lets a program read and change the contents of a mailbox — messages, calendar events, contacts, tasks and folders — without going through the Outlook interface a person would use.

It is a server-side API, not a mail app. A backup tool, a CRM, a room-booking system or a signature manager uses EWS to reach many mailboxes at once. That is different from a protocol such as IMAP, which a single person's mail client uses to fetch their own mail.

How does EWS work?#

An EWS client sends a request as a SOAP envelope — an XML document — over HTTPS to a single endpoint on the Exchange server, and the server replies with XML. Most developers use the EWS Managed API, a .NET library that wraps the raw SOAP calls, though you can also call the service directly.

Clients rarely hard-code the address. They use Autodiscover, a Microsoft service that returns the correct EWS endpoint for a given mailbox. Authentication once relied on Basic auth or NTLM; in Exchange Online, Basic auth for EWS has been retired, so an app now signs in with OAuth 2.0.

One feature made EWS especially popular for service apps: impersonation. EWS impersonation lets a service account, granted the right role, act as though it were another user. One application can then reach thousands of mailboxes without holding each person's password. Backup, archiving, migration and CRM tools leaned on this heavily. That broad reach is also part of why Microsoft is tightening EWS — per Microsoft's documentation, the January 2024 Midnight Blizzard security incident involved EWS and raised the urgency of retiring it.

Is EWS being deprecated, and when does it stop working?#

Yes. Microsoft announced in 2018 that EWS would receive no new features, and in 2023 it set a date to switch EWS off in Exchange Online. As of August 2026, Microsoft's own documentation describes a phased shutdown rather than a single cut-off — and the exact timing can vary by tenant, so check the source page, because this timeline has moved before.

What breaks when EWS is switched off#

When EWS is disabled, any app that still calls it against an Exchange Online mailbox stops working. That includes older mail clients, backup and e-discovery tools, migration utilities, room and resource booking systems, CRM sync, email signature managers and in-house scripts.

The fix is to move those apps to Microsoft Graph. Microsoft publishes EWS usage reports in the Microsoft 365 admin center and an EWS analyzer tool to help you find what still depends on EWS before the deadline. End users do not need to do anything — Microsoft is also removing EWS from its own products, such as Outlook, Office and Teams.

EWS vs Microsoft Graph: what replaces it#

Microsoft Graph is the replacement. It is a single REST API for Microsoft 365 — not just mail, but calendars, contacts, Teams, files, users and more — using JSON instead of XML. Microsoft says Graph has near-complete parity with EWS for most scenarios, but as of 2026 a few gaps remain, such as mailbox import and export and some public-folder access.

Common misconceptions about EWS retirement#

• Myth: EWS is disappearing everywhere. Reality: the retirement is for Exchange Online only. Exchange Server on-premises keeps EWS.
• Myth: EWS stops on a single day. Reality: it is phased — disablement starts October 2026 and completes by April 2027, and admins can turn it off sooner or gate it with an app allow-list.
• Myth: as an Outlook user I need to migrate something. Reality: the retirement targets apps and integrations that call EWS, not people reading mail in Outlook.
• Myth: Microsoft Graph is just EWS with JSON. Reality: it is a different model with broader scope, and as of 2026 it is near-parity but not identical.
• Myth: EWS is the same as MAPI, ActiveSync or IMAP. Reality: those are separate protocols; EWS is a SOAP web-service API for programmatic mailbox access.

Where AI Emaily fits#

You might be reading this because an app you rely on is about to lose EWS access, so it is worth being clear about what a mail client can and cannot do for that. AI Emaily is a mail client — an AI chief of staff that helps triage your inbox and draft replies — not an EWS integration and not a migration tool. It connects to your Outlook or Microsoft 365 mailbox through Microsoft's modern OAuth sign-in, the Graph-based connection Microsoft now recommends, rather than the EWS endpoint being switched off, so the retirement does not change how you add an account.

What it does not do is move a custom in-house app or a third-party tool off EWS; for that you need Microsoft's EWS-to-Graph mapping and analyzer tools, and usually a developer. We build AI Emaily. If you want the mail that reaches your Microsoft 365 inbox triaged and drafted for you, that is the job we do.