What happened
Microsoft's long-announced retirement of Exchange Web Services in Exchange Online reaches its first hard milestone on October 1, 2026, when EWS access for non-Microsoft applications will be disabled by default across tenants. Organizations that still need legacy access can be excluded from that automatic cutoff, but only if administrators set the EWSEnabled property to true and configure an allow list of approved application IDs before the end of August. Even then, the reprieve is temporary: EWS shuts down permanently on April 1, 2027, with no exceptions. The retirement applies only to Exchange Online in Microsoft 365; on-premises Exchange servers are unaffected. Microsoft's replacement is the Graph API, and vendors including Veeam and Mimecast have published their own migration guidance for products that historically depended on EWS.
Why it matters for your business
EWS is plumbing most business owners have never heard of, which is exactly why this deadline bites. It is how many older email backup tools, CRM connectors, email security services, journaling and archiving products, and even scan-to-email features on multifunction printers talk to Exchange mailboxes. When Microsoft flips the default on October 1, businesses that never checked will find out about their hidden dependencies when a backup silently stops running or a scanner stops delivering. Microsoft 365 is the backbone of most small offices in this region, so this is worth an hour of attention now instead of an emergency later.
What to do about it
- Ask your IT provider to pull the EWS usage report in the Microsoft 365 admin center to see which applications still use it
- Contact vendors of any flagged tools, especially backup, archiving, and CRM products, and confirm they support Microsoft Graph
- If a critical tool cannot migrate before October, configure the allow-list exception before the end of August, and treat April 1, 2027 as the real deadline