Microsoft retires EWS: What it means for Microsoft 365 to Zoho Mail migrations

Microsoft has officially announced the retirement of Exchange Web Services (EWS) for Exchange Online. Microsoft has been moving away from EWS for several years now: it stopped receiving new feature updates back in 2018, and basic authentication support for EWS was retired in 2020. 

For organizations planning a migration from Microsoft 365 to Zoho Mail, this announcement brings an important consideration, especially for businesses that rely on in-place archive mailboxes.

Update - September 2026: 

Earlier in August 2026, we highlighted that Microsoft's planned retirement of EWS would directly impact the migration of In-Place Archive Mailboxes from Microsoft 365 and Exchange Online to Zoho Mail. Microsoft has since introduced EWSAllowedAppIDs, a setting that allows M365 and Exchange Online administrators to specify applications that can continue accessing EWS after service blocking begins on October 1, 2026.

For Zoho Mail migrations, this update grants a vital grace period. Administrators can now explicitly allow the Zoho Mail application to maintain EWS access, extending the window to migrate In-Place Archive Mailboxes until EWS is fully retired on April 1, 2027.

What is EWS, and why does it matter?

Exchange Web Services (EWS) is a legacy Microsoft API that enables external applications to access and interact with mailbox data stored in Exchange Online. It has been widely used for mailbox migrations, integrations, archiving solutions, and third-party email management tools. 

How EWS retirement affects migration to Zoho Mail

As part of its broader modernization strategy, Microsoft recommends that organizations transition to the Microsoft Graph API for all Exchange Online integrations. Zoho Mail has also moved its supported Microsoft 365 and Exchange Online migration workflows to Microsoft Graph.

However, Microsoft Graph does not currently support access to In-Place Archive Mailboxes in Microsoft 365 and Exchange Online. As a result, Zoho Mail must temporarily continue using EWS specifically to fetch and transfer In-Place Archive data.

• Before October 1, 2026: We strongly recommend completing your In-Place Archive migrations before EWS service blocking begins to avoid extra tenant configurations.
• After October 1, 2026: If you need to migrate archives after service blocking starts, you must grant Zoho Mail continued access using Microsoft’s EWSAllowedAppIDs setting.

Enabling EWS access using EWSAllowedAppIDs

The EWSAllowedAppIDs feature gives administrators granular control over which applications are permitted to bypass EWS blocking during the deprecation phase.

If your archive migrations extend past October 1, 2026, simply add the Zoho Mail Application ID to your organization's EWSAllowedAppIDs allowlist. This ensures uninterrupted access for archive transfers throughout Microsoft's transition period.

For information on configuring EWSAllowedAppIDs and adding the Zoho Mail Application ID, see our detailed help document.

Note: Please note that this is a temporary extension. EWSAllowedAppIDs will only remain functional until April 1, 2027, when EWS is decommissioned entirely from Microsoft. After this hard deadline, EWS can no longer be used to access or migrate In-Place Archive Mailboxes.

EWS retirement timeline

The timeline below outlines the key milestones in the EWS retirement process and how each phase impacts your In-Place Archive migration to Zoho Mail.

Planning your Microsoft 365 archive migration

To ensure a seamless transition, plan your archive migration strategy around your preferred timeline, either wrapping up before October 1, 2026, or leveraging the EWSAllowedAppIDs extension up to April 1, 2027.

Here is how you can prepare:

• Identify users with in-place archive mailboxes: In your Microsoft 365 or Exchange Online Admin Center, identify all users who have in-place archive mailboxes enabled and assess the total data volume. This will help you estimate migration duration and plan your timeline effectively.
• Configure the migration in Zoho Mail: Log in to the Zoho Mail Admin Console and navigate to Data Migration. Add the required server details and migration settings for your Microsoft organization. When adding users, select In-Place Archive Mailbox under MailboxType for the relevant accounts. 

• Prioritize critical data: Users with large or business-critical archives can be marked as Priority to ensure their data is migrated first. Once the configuration is complete, start the migration. 

  For step-by-step guidance, refer to our Migration from Microsoft 365 to Zoho Mail help page. 

Archive mailbox migration after EWS retirement

Organizations that do not complete their In-Place Archive migrations before April 1, 2027, risk losing the ability to move archived mailbox data directly from Exchange Online to Zoho Mail, unless Microsoft releases an equivalent archive API via Microsoft Graph in the interim.

If you are evaluating Zoho Mail as an alternative to Microsoft 365, explore our detailed comparison guide here. For assistance with migration planning or execution, contact us at support@zohomail.com. Our team will be happy to help you assess your requirements and ensure a successful transition to Zoho Mail.

FAQs

1. When is Microsoft retiring EWS?

Microsoft is retiring EWS in two phases: EWS requests begin getting blocked in Exchange Online starting October 1, 2026, and EWS is fully removed from Exchange Online on April 1, 2027.

2. Will Zoho Mail migration from Microsoft 365 stop after EWS retirement?

No. The retirement only affects the migration of in-place archive mailboxes. Migration of primary mailboxes, contacts, calendars, and shared mailboxes from Microsoft 365 to Zoho Mail will continue to be fully supported.

3. What is the deadline to migrate Microsoft 365 in-place archive mailboxes to Zoho Mail?

We recommend completing In-Place Archive Mailbox migrations before October 1, 2026, when EWS service blocking begins. However, administrators can extend this deadline up to April 1, 2027, by adding Zoho Mail's application ID to Microsoft's EWSAllowedAppIDs allowlist. Learn more.

4. Can archived mailbox data be migrated after April 1, 2027?

No. EWS will be completely retired from Exchange Online on April 1, 2027. After this date, In-Place Archive Mailbox migration to Zoho Mail will no longer be possible via EWS. This may change only if Microsoft introduces alternative API support for archive mailboxes in the future.

5. Is EWS being deprecated for on-premise Exchange?

No. The retirement of EWS applies only to Microsoft 365 and Exchange Online; there are no changes to EWS in Exchange Server, and EWS will continue to be fully supported for Exchange on-premise mailboxes and deployments.