Mimecast and the EWS retirement

Threat Remediation

Status

Moved to Microsoft Graph

Date

2026-09-08

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/50480121633811

“A Graph API migration path is available. You should migrate to the new Graph API connector”

Microsoft Exchange Web Services (EWS) Retirement - EOL - Jun 2026 (Mimecast Support) (2026-09-08), read 2026-10-14.

What to do. A Graph connector is available. Migrate the remediation integration to it; after that the old EWS connector app no longer needs the allow list.

Sync & Recover Cloud Gateway

Status

Moved to Microsoft Graph

Date

2026-10-12

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/52527669230995-Sync-Recover-Migrating-Connectors

“Phase 2: Data conversion and switchover to Graph (now live, handled by Mimecast)”

Sync & Recover - Migrating Connectors (Mimecast Support) (2026-10-12), read 2026-10-14.

What to do. Run Migrate (Phase 1) in the Mimecast console to add Graph permissions; Mimecast then converts mailboxes to Graph one by one. Keep the app on EwsAllowedAppIDs until conversion is complete. The Restore component is being discontinued.

Sync & Recover Cloud Integrated (Restore)

Status

Retired

Date

2026-09-08

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/50409601815315-Microsoft-Exchange-Web-Services-EWS-Retirement-EOL-Jun-2026

“Will be discontinued. Replacement may be available in the future if Microsoft addresses current Graph API parity gaps.”

Microsoft Exchange Web Services (EWS) Retirement - EOL - Jun 2026 (Mimecast Support) (2026-09-08), read 2026-10-14.

What to do. Sync already runs on Graph; only Restore uses EWS, and Restore is being discontinued. Keep the app on EwsAllowedAppIDs if you need Restore until EWS ends.

Continuity for Office 365 (Event Monitor)

Status

Migration announced

Date

2026-09-08

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/50409601815315-Microsoft-Exchange-Web-Services-EWS-Retirement-EOL-Jun-2026

“New Graph API connector planned in the coming months. A migration guide will be provided.”

Microsoft Exchange Web Services (EWS) Retirement - EOL - Jun 2026 (Mimecast Support) (2026-09-08), read 2026-10-14.

What to do. A new Graph connector is planned and must be set up by hand when Mimecast releases it. Keep the Mimecast O365 Continuity app on EwsAllowedAppIDs until then.

Mimecast Synchronization Engine (MSE)

Status

Retired

Date

2026-09-08

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/55196651141395

“Will be discontinued in its current form. A new agentless, UI-based alternative is targeted for December 2026.”

Microsoft Exchange Web Services (EWS) Retirement - EOL - Jun 2026 (Mimecast Support) (2026-09-08), read 2026-10-14.

What to do. MSE features that use EWS end: storage management and managed folders with no replacement, folder and calendar replication with a new agentless tool targeted for December 2026. Keep the MSE OAuth app on EwsAllowedAppIDs until you move off it.

Simply Migrate (Archive Mailbox)

Status

Retired

Date

2026-09-08

Vendor notice

https://mimecastsupport.zendesk.com/hc/en-us/articles/50409601815315-Microsoft-Exchange-Web-Services-EWS-Retirement-EOL-Jun-2026

“Simply Migrate - Archive Mailbox Will be permanently discontinued. No replacement planned”

Microsoft Exchange Web Services (EWS) Retirement - EOL - Jun 2026 (Mimecast Support) (2026-09-08), read 2026-10-14.

What to do. Archive mailbox migration through Simply Migrate ends when EWS ends, with no replacement. Finish archive migrations before 1 April 2027.

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