PoliteMail uses EWS for a narrow set of operations: ExpandGroup (list expansion), ResolveName (recipient and group-type resolution, also used as the credential test), GetUserAvailability (recipient working hours, time zone, and mailbox language for scheduled sends), and Autodiscover on the basic-auth path. Server-side calls use EWS impersonation. Where Graph provides equivalent coverage, PoliteMail already uses Graph.
The exposure is concentrated in list expansion.
| List /Group Type | Graph | EWS |
|---|---|---|
Local contact group (Outlook) | N/A (MAPI, desktop only) | N/A |
Mailbox contact group | Supported | Supported |
Security group | Supported | Supported |
Universal / static distribution group | Supported | Supported |
Microsoft 365 group | Supported | N/A |
M365 Dynamic Group (Entra) | Supported | N/A |
Exchange Dynamic Distribution List (DDL) | Not supported | Supported |
Distribution groups with hidden membership | Supported | N/A (hidden members are silently omitted) |
Exchange Online DDLs are the gap. PoliteMail engineering confirmed by testing that once Set-OrganizationConfig -EwsEnabled:$false is applied to a tenant, DDLs cannot be expanded, even when the application holds full_access_as_app. Microsoft's replacement is a DynamicDistributionGroupMember endpoint in the Exchange Online Admin API (a REST wrapper over Get-DynamicDistributionGroupMember, separate from Microsoft Graph). It is in preview, not available in all organizations, and PoliteMail does not use it today. It is not safe to plan around it landing in PoliteMail before enforcement.
What is NOT Affected
The following areas will not be affected by the deprecation of EWS:
- On-premises Exchange. EWS in Exchange Server is not part of this retirement. Hybrid organizations should note that Exchange Online mailbox traffic is still in scope.
- Outlook for Windows and Mac, Teams, and other Microsoft first-party clients. Microsoft is removing its own EWS dependencies separately; your users' Outlook experience does not change because of this.
- PoliteMail message transmission and tracking. Outbound mail is sent over Microsoft Graph or SMTP, and open and click measurement never touches EWS.
Two parts of the send path can still depend on EWS and are covered by our provided action plan:
- Server-side list expansion at send time. If Graph is not configured, the server expands recipients over EWS ExpandGroup before queueing the send.
- Recipient working hours and time zone data. The Archive service refreshes contact time zone, working days, and mailbox language over EWS GetUserAvailability when the expansion mode is EWS. That data drives recipient-time-zone and working-hours-only scheduling. With Graph configured this data comes from Graph instead.
