Fast, private mail for Microsoft 365.

Prism Mail talks directly to Microsoft — your email lives on your device and their cloud, and doesn't pass through ours. No accounts to create, nothing in between.

Coming Soon

The iPhone app is on its way to the App Store, and the Windows 11 app is coming to the Microsoft Store — this page will flip to download buttons as each goes live.

The same design on both platforms

No servers in between

The app connects directly to Microsoft 365. Prism operates no mail servers and keeps no copies of your mail.

Sign in with Microsoft

You sign in on Microsoft's own sign-in pages with the Microsoft 365 account you already have. There is no Prism account to create, and the app does not receive your password.

What each app does

The two apps share the same Microsoft 365 core, and each is built natively for its platform. Here is exactly what ships in each.

Prism Mail for iPhone

Coming soon to the App Store

Microsoft 365 sign-in (single account)
Folder list with unread counts, and a fast message list with sender, subject, preview, and read state
Full HTML message reading; remote images do not load, while images embedded inside the message display
Compose, reply, reply all, and forward — replies keep the conversation thread, and forwards include the original's attachments
Open and preview received attachments in the app — PDFs, images, Office documents (including Excel .xlsx and 97-2004 .xls), and text files
Attach files from the Files app when composing, up to 3 MB per file
Swipe to archive or delete, automatic mark-as-read, and pull-to-refresh
Plain-text signature with include modes: off, new emails only, or every email
Links open in an in-app Safari view, kept separate from your mail
Follows your iPhone's light or dark appearance
In the free version, a short Prism Mail promotional line is included below your signature on every email you send

Prism Mail for Windows 11

Coming soon to the Microsoft Store

Three-pane layout: folders, message list, and reading pane
Signature designer with an embedded logo that travels inside the message itself, so it can display for recipients whose clients block remote images, including classic Outlook
Banner generator and a logo-to-linked-text converter (local OCR), with a live signature preview
Paste images into compose, recipient autocomplete, and contacts with address books and optional auto-capture from senders' signatures
New-mail notifications via Windows toasts, background sync, and refresh on focus
A link chooser for email links, plus a built-in sandboxed browser kept separate from your mail
Theme follows Windows, with a manual Auto / Dark / Light toggle
Stays signed in across restarts, with the sign-in token cache encrypted at rest

Feature lists describe the current builds and may change as the apps evolve.

Private by architecture, not by promise

Prism Mail stores your mail on your device and talks only to Microsoft. There are no Prism mail servers to trust, because there are no Prism mail servers at all — your mail isn't read, mined, or monetized by us. It stays between your device and Microsoft.

Need a hand?

Questions, bug reports, or feedback about Prism Mail? Send us a note and we'll get back to you.