Email App Usage Report

Track which email clients your users are accessing Exchange Online with. Monitor adoption of modern clients and identify users on legacy or unsupported email applications.

Overview

The Email App Usage Report shows a breakdown of email client usage across your organization, including Outlook desktop, Outlook mobile, Outlook on the web (OWA), and third-party clients. This data helps plan migration efforts and enforce security policies around supported clients.

Report Columns

Column	Description
User	Display name and email address
Outlook Desktop	Whether the user has accessed via Outlook for Windows/Mac
Outlook Mobile	Access via Outlook for iOS or Android
Outlook Web (OWA)	Access via the web browser client
POP3/IMAP	Access via legacy protocols
Other Apps	Third-party email clients
Last Activity Date	Most recent activity from any client
Platform Details	Operating system and version of the client

Client Distribution

The report provides aggregate statistics showing the percentage of users on each client:

Outlook Desktop — Windows and macOS desktop application
Outlook Mobile — iOS and Android mobile application
Outlook Web (OWA) — Browser-based access
Third-Party Clients — Non-Microsoft email clients
Legacy Protocols — POP3, IMAP, and SMTP direct connections

Note: Users accessing via legacy protocols (POP3/IMAP) may pose a security risk as these protocols do not support modern authentication. Consider disabling legacy authentication.

Filters

Date Range — Last 7 days, 30 days, 90 days, or custom
Client Type — Outlook Desktop, Mobile, OWA, Legacy, Third-party
Platform — Windows, macOS, iOS, Android, Web
User Status — Active, Inactive
Tenant — Filter by managed tenant

Security Considerations

Identify users still using Basic Authentication via legacy protocols
Track adoption of Outlook Mobile for mobile device management compliance
Monitor third-party client usage that may bypass DLP policies
Ensure all clients support modern authentication (OAuth 2.0)

Graph API Data Sources

GET /reports/getEmailAppUsageUserDetail
GET /reports/getEmailAppUsageAppsUserCounts
GET /reports/getEmailAppUsageVersionsUserCounts

API Reference

GET /api/reports/exchange/email-app-usage — Get email app usage report
GET /api/reports/exchange/email-app-usage/summary — Get aggregated client statistics
POST /api/reports/exchange/email-app-usage/export — Export report data