Are You Affected?
You are likely affected if all three of the following apply to you:
● You use the Exchange email features in DPS (Email Agent, calendar sync, etc.)
● Your email is hosted in Microsoft 365 / Office 365 (cloud-hosted, not on your own server)
● You have the OAuth 2.0 option enabled in your company's Email Settings in the DPS Config Tool
Quick check: If you have an App Registration set up in your organisation's Azure Portal (Entra ID) specifically for DPS — you set this up following our OAuth 2.0 setup guide — then you are using this configuration and should read on.
If you're not sure, or if you use a traditional username/password (basic auth) setup for an on-premises Exchange server, you are not affected by this change.
What Will Happen If You Don't Act
From 1 October 2026, Microsoft will begin automatically blocking EWS connections for Microsoft 365 tenants that have not opted in to keep EWS enabled. If your DPS software connects via OAuth 2.0 to Exchange Online and no action is taken, you may experience service interruptions to email and calendar features from that date.
What You Need to Do
This is a quick configuration change in your Microsoft 365 tenant — it does not require any changes to DPS itself. You will need someone with Exchange Online administrator access to your Microsoft 365 tenant to complete this.
Step 1 — Find Your DPS App ID
Your App ID (also called Client ID) is the GUID you noted down when setting up OAuth 2.0 for DPS. You can find it in:
● The DPS Config Tool → Company → Email Settings (the Client ID field), or
● Azure Portal → Azure Active Directory → App Registrations → your DPS app → Application (client) ID
Step 2 — Open Exchange Online PowerShell
Connect to Exchange Online PowerShell using an admin account:
Connect-ExchangeOnline
Step 3 — Enable EWS and Add Your App ID to the Allow List
Run the following two commands, replacing the placeholder with your actual App ID:
Set-OrganizationConfig -EWSEnabled $true
Set-OrganizationConfig -EWSAllowedAppIDs @("your-dps-app-id-guid-here")
Step 4 — Verify
Confirm the settings have applied:
Get-OrganizationConfig | Select EWSEnabled, EWSAllowedAppIDs
This should show EWSEnabled = True and your App ID listed.
Deadline
Action required before 31 August 2026. Tenants that configure the Allow List before this date are excluded from Microsoft's automatic October 1st block. After this date, you risk a service interruption while the settings are corrected.
Need Help?
We have attached our OAuth 2.0 for Office 365 EWS – DPS Setup Guide for reference, which walks through the original App Registration process if you need to locate your credentials.
If you are unsure whether you are affected, or need assistance identifying your App ID or completing these steps, please contact our Support team who will be happy to help.
This change affects Exchange Online (Microsoft 365) only. On-premises Exchange Server installations are not affected.