Letterblade

Open and read Outlook .msg files — no Outlook required.

Download for macOS (Apple Silicon) Download for Windows (x64) Download for Linux (x86_64)

Version 1.0.0 · code-signed on macOS and Windows · Java runtime bundled · available on all three desktop platforms.

What you get

Someone sends you a .msg file. You don’t have Outlook — you’re on a Mac, or you simply never installed it. Letterblade opens the file and shows you the message the way it was meant to be read: formatting, inline images, attachments, the works.

Open it your way. Drop a .msg file onto the window, or use Open.
The message as intended. HTML mail renders with its formatting and inline images; a plain-text view is one click away.
The envelope at a glance. From, To, CC, date, and subject sit above the message.
Attachments, on your terms. Each attachment appears as a chip — save it to disk, or hand it to your usual application. Nothing ever opens by itself.
Messages inside messages. A forwarded message attached as .msg opens in its own window, attachments and all.
Copy that works. Select all and copy give you clean text from the message itself.

Letterblade rendering an HTML newsletter with an inline image

Private by default

Email is a favourite delivery route for tracking and worse, so Letterblade is careful on your behalf:

Remote images are blocked until you ask for them. Tracking pixels stay blind; a bar tells you how many images were held back, and one click loads them for that message only.
Scripts and active content are stripped before the message is rendered.
Attachments never run or open automatically — you decide what happens to each one.
Your mail stays on your machine. Letterblade reads files locally; nothing is uploaded anywhere.

Which direction next?

Letterblade does one thing today: it opens .msg files and treats them with care. Where it goes from here is decided the honest way: by whoever turns up and asks. So, what do you want? Open an issue (or 👍 an existing one) and say what you’d use it for:

A message that didn’t open, or didn’t look right — the most valuable report of all. Describe the message rather than attaching it; mail is private, and yours stays that way.
More formats — .eml, mbox, or something more exotic.
Doing more with a message — search inside it, print it, save it as PDF or HTML.
A dark theme.
Something that isn’t on this list — often the best kind.

Download

Platform	Installer	Version	Status
macOS (Apple Silicon)	`.dmg`	1.0.0	Available
Windows 10 / 11 (x64)	`.msix`	1.0.0	Available
Linux (x86_64)	`.AppImage`	1.0.0	Available

Verify the download:

# macOS — v1.0.0
shasum -a 256 Letterblade.dmg
# d868e2d5a68c1eab40bbc88d1e1f8d7c16286f41ee1bc6134fecfe1da966fb5e

# Windows (PowerShell) — v1.0.0
Get-FileHash Letterblade.msix -Algorithm SHA256
# a4d684936c199a874cc0045753adb9f46a7ad184554770986fdaa9b635048fcc

# Linux — v1.0.0
sha256sum Letterblade.AppImage
# 8f92114752bfd7a0598913d6d670165ce223f2bbb3863e32eac27069a8057a62

macOS — signed with an Apple Developer ID and notarized by Apple, so it opens with no Gatekeeper warning. You can verify with spctl -a -vv /Applications/Letterblade.app — it reports a Developer ID signature with Team ID F537XPA69T. Installed copies check for new releases and update themselves.

Windows — the .msix is Authenticode-signed and timestamped; Windows shows a verified publisher on install. As a new individual publisher, SmartScreen may still show a “Windows protected your PC” prompt on first download until the app builds reputation — click More info → Run anyway to proceed. Installed copies check for new releases and update themselves.

Linux — the .AppImage is a single self-contained file: make it executable (chmod +x Letterblade.AppImage) and run it, no installation and no root. It is unsigned, as AppImages generally are — verify the SHA-256 above if you want certainty about what you downloaded. Installed copies check for new releases, swap themselves in place and ask you to restart.

Requirements

macOS 12 Monterey or later (Apple Silicon), Windows 10 / 11 (x64), or Linux (x86_64) with FUSE available — the usual requirement for running any AppImage. The Java runtime is bundled — no separate JDK needed.
.msg files as produced by Outlook (classic and modern Windows formats, RTF-encapsulated HTML included).