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1 October 2026 Retirement Date Set for Exchange Web Services
On September 19 2023, Microsoft announced their intention to retire the Exchange Web Services (EWS) protocol on 1 October 2026 and replace it with Graph APIs. The retirement only affects non-Microsoft apps. Microsoft 365 apps like Teams can continue to use EWS to read data from Exchange Online mailboxes. EWS continues to be supported for Exchange Server as the Graph API is unavailable for on-premises servers.
Three years seems like a long way off. However, an extended period is needed by app developers to convert EWS code to Graph API requests. There shouldn’t be much difficulty in recreating code dealing with accounts, mailboxes, and calendars. Microsoft knows that the problems lie in areas not covered by the Graph API, such as archive mailboxes and public folders.
The Management Gap
Two particular topics deserve comment. First, if you’ve used EWS to develop management tools for Exchange, it’s likely that you’re going to find big gaps. Over recent years, the Exchange developers have concentrated on modernizing the Exchange Online management PowerShell module to remove dependencies like WinRM, remove support for basic authentication, and make the most heavily used cmdlets more robust and reliable. There’s no doubt that Exchange PowerShell works better now than it did, but a gap exists in coverage of Exchange management within the Graph APIs. There are many actions in the Exchange admin center that can’t be performed through a Graph request.
You might be able to bridge the functionality gap with PowerShell cmdlets, but if you want to swap EWS code for Graph code, you’ll probably have to wait until Microsoft extends support for management operations to the Graph APIs.
The Backup Conundrum
Microsoft did not design EWS to function as a backup/restore mechanism. Even so, the lack of a formal backup API for Exchange over the years led backup vendors to develop products around EWS. This situation persists today as all backup products currently available for Exchange Server and Exchange Online use EWS (Microsoft’s announced but not yet available Syntex Backup for Exchange Online uses a different API).
Other ISVs use EWS to move data into Exchange Online. Examples include transferring data migrated from a legacy archive system or tenant to tenant migrations.
Discussion of how EWS-based data transfer products can move to a replacement API was notably missing from Microsoft’s announcement. The simple fact is that Microsoft has no publicly-available backup API for Exchange Online. One needs to be created and tested to ensure that it works as least as well as EWS (which has some issues with throttling and robustness) before a transition is possible. There’s no word on such a replacement yet. And Microsoft’s saying nothing either about the possibility that any replacement will be a metered (paid-for) API such as the Teams Export API. Hopefully, Microsoft will ensure that any transition for ISVs away from EWS to replacement APIs will be cost neutral.
Well-Known Gaps Remain Unclosed
The gaps discussed here are not unknown. Customers and Microsoft have debated what’s missing for Exchange in the Graph APIs for several years but little has happened to close the gaps. A certain scepticism exists that Microsoft will suddenly swing into action to produce a bunch of updates to support Exchange Online management, archive mailboxes, and so on. The ball is in Microsoft’s court to prove to the development community and customers that Exchange Online has truly embraced the Graph APIs for all aspects of the product. Let’s hope that they get the work done.
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Quick question: If you use “Office 365 Exchange Online” Graph with this API permission, isn’t that solving the backup problem you mentioned?
“full_access_as_app”
No. You need permissions to access mailbox data before you can stream it out. I believe you’re referring to the Graph role that allows an app to manage Exchange Online. You’d need Mail.Read.All to be able to open and read all mailboxes. See this example: https://practical365.com/mailbox-clean-up-script/
Apart from reading the information, you’d need to be able to stream the data in a robust and secure manner to a backup target, make sure that all the data arrived as expected, and so on. That’s the kind of work done by a backup API.