Platform support
The add-in runs on every Outlook surface that supports Office.js add-ins. Each surface reports back to the portal under its own platform icon in the Observed Versions card.
| Platform | Office host token | Notes |
|---|---|---|
| Outlook on the web (OWA) | OfficeOnline | All modern browsers (Edge, Chrome, Safari, Firefox). Works on Mac and Windows. |
| New Outlook for Windows | Universal | The Edge-WebView2-based client. Same browser engine as OWA but reported separately so you can tell them apart. |
| Classic Outlook for Windows | PC | The traditional desktop client. Uses WebView2 internally too, but Office.js identifies it explicitly. |
| Outlook for Mac | Mac | Both Apple Silicon and Intel. Uses Apple's WebKit. |
| Outlook for iOS | iOS | iPhone + iPad. |
| Outlook for Android | Android | Phones + tablets. |
Minimum supported Office requirement set
The add-in declares Mailbox 1.5 in the manifest. That means it works on any Office client released after July 2016. We don't yet require anything more recent — we rely only on documented APIs in 1.5.
If you need to support an older client, contact us. We can sometimes ship a constrained manifest that targets an earlier requirement set.
Single Sign-On (SSO)
The add-in uses Office's Nested App Authentication (NAA) to acquire an access token without a popup. NAA is the modern path; older clients without NAA support fall back to the Office Dialog API, which opens a small auth popup.
If neither path works, the add-in surfaces a "Sign in" button that opens MSAL in a regular popup. This usually only happens on browsers with very strict pop-up policies or older Outlook builds.
Browser support
OWA-side, the add-in supports:
- Chrome / Chromium (latest two versions)
- Edge (latest two versions)
- Safari 16+
- Firefox (latest version)
We don't test against IE 11 — Microsoft retired Outlook on the web support for it years ago.
Limitations
- Outlook on the web in classic mode — Microsoft is retiring this. The add-in still works on it but we don't add new features.
- Outlook for Mac (Legacy) — the pre-2020 Mac client. Not supported.
- Shared mailboxes — the add-in shows the signed-in user's quarantine, not the shared mailbox's. Quarantine for shared mailboxes belongs to the named recipient.