Microsoft is retiring the legacy Exchange Web Services (EWS) interface in the Microsoft 365 cloud. For many years, archiving, backup, CRM and other applications connected to mailboxes through EWS. If such an application in your company or at your customers still uses EWS, it may stop working without any warning.
Key dates
- 1 October 2026 – Microsoft started phasing out EWS in Exchange Online. EWS is blocked unless the administrator created an allow list of applications (AppID AllowList) in advance and kept EWS enabled.
- 1 April 2027 – EWS in Exchange Online is retired permanently, with no option to re-enable it.
These changes apply to Microsoft 365 (Exchange Online) mailboxes. Applications have to move to the Microsoft Graph API – the path Microsoft itself recommends.
What to check now
- In the Microsoft 365 admin center, review the EWS Usage Reports – they show which applications still connect through EWS.
- Ask the vendor of each such application when it will move to Microsoft Graph, and update it to the latest version.
- Pay special attention to email archiving and backups: if they stop, you will only find out when you need an old email.
MailStore already works through Microsoft Graph
MailStore Server and MailStore Service Provider Edition archive Microsoft 365 mailboxes through the Microsoft Graph API. Since version 26.2 the vendor has simplified the move to the Graph API and IMAP, and version 26.4, released on 14 October 2026, made archiving via Graph even more stable: the program handles Microsoft throttling and delays better, and timeouts can be configured more flexibly.
If you have been using MailStore for a while and your update and support service has expired, you will not get the latest version – it has to be renewed first. We can help with that.
For partners
The EWS retirement is a good reason to contact customers who use Microsoft 365: check their archiving solution and offer a move to MailStore. In the partner zone you will find your prices, and for larger projects we prepare an individual offer within one business day.
Become a partner and see your MailStore prices
Business enquiry – an offer within 1 business day
How an IT company can become a software license reseller
Sources: Microsoft (Deprecation of Exchange Web Services in Exchange Online; message MC1227454), MailStore (version 26.4 release notes, 14 October 2026).