Microsoft API Credentials
New Campaign
Microsoft API Connected
1 OAuth app(s) registered · 1 / 100 sender slots used
Registered OAuth Apps
New sender connections are apportioned across these apps automatically
Name Client ID Tenant Used Limit
Default 86687851…971a common 1 100
Safe to add or remove anytime. Existing senders store their own tokens and keep sending normally. Only new accounts connected after a change will use the updated set of apps.
How to Get Credentials
Azure Active Directory app registration guide
1
Go to Azure Portal → Microsoft Entra ID → App registrations → New registration.
2
Set Supported account types to "Accounts in any organizational directory and personal Microsoft accounts" (multi-tenant + personal).
3
Under Redirect URI, choose Web and add exactly:
https://mailengine.online/oauth/microsoft/callback
4
Copy the Application (client) ID from the Overview page into the form on the right.
5
Go to Certificates & secrets → New client secret. Copy the secret Value (not the Secret ID) into the form.
6
Go to API permissions → Add a permission → Microsoft Graph → Delegated permissions and add Mail.Send, User.Read, and offline_access.
Add OAuth App
Enter your Azure AD app registration details
Azure AD apps in testing/dev typically cap out around 100 connected accounts.
Use the secret Value shown once at creation time, not the Secret ID
"common" supports both personal Outlook/Hotmail and work/school Microsoft 365 accounts. Use a specific tenant ID to restrict to one organization.
https://mailengine.online/oauth/microsoft/callback
No disruption to existing senders. Each connected Outlook account stores its own access & refresh tokens independently. Adding a new app only affects accounts connected after the change.
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