How to Open .msg Files on Any Device or Platform
If you've received a .msg file and can't figure out how to open it, you're not alone. These files look like any other email attachment, but they don't behave like a standard document. Understanding what they are — and why they're trickier than they appear — is the first step.
What Is a .msg File?
A .msg file is a proprietary email message format created by Microsoft. When you save an email directly from Microsoft Outlook, it gets stored as a .msg file, preserving not just the message body but also metadata like the sender, recipient, timestamp, attachments, and formatting.
Unlike a standard .eml file (which is plain text-based and widely compatible), .msg files are encoded in Microsoft's Compound Document File Format (CFDF) — a binary format that requires specific software to decode correctly. This is why double-clicking a .msg file on a non-Windows machine, or on a machine without Outlook installed, often results in nothing opening at all.
The Easiest Method: Microsoft Outlook
If you have Microsoft Outlook installed (Windows or macOS), opening a .msg file is straightforward:
- Locate the .msg file in File Explorer or Finder
- Double-click it — Outlook should open it automatically
- If it doesn't, right-click and choose "Open with" → Microsoft Outlook
This is the most complete way to view .msg files. Outlook renders all formatting, embedded images, and attachments exactly as intended. No conversion, no data loss.
The catch: Outlook is a paid application (typically through a Microsoft 365 subscription). If you don't already have it, this path has a cost attached.
Opening .msg Files Without Outlook 📧
This is where setup matters significantly. Several alternatives exist, each with trade-offs.
Free Desktop Applications
Mozilla Thunderbird combined with the MsgViewer add-on (or similar extensions) can open .msg files on Windows, macOS, and Linux. The results are generally reliable for plain-text and basic HTML emails, though complex formatting or embedded objects sometimes don't render perfectly.
MSGViewer Pro and Free MSG Viewer are standalone Windows utilities specifically built to read .msg files without Outlook. They're lightweight and don't require installation in all cases. Quality of rendering varies by tool, especially for emails with rich HTML or multiple attachments.
Web-Based Viewers
Several browser-based tools let you upload a .msg file and view its contents online. These work on any operating system — including Chromebook, Linux, or macOS without Outlook — since processing happens in the browser or on a server.
⚠️ Important consideration: uploading .msg files to third-party web services means your email content (including any sensitive data, names, attachments, or internal communications) leaves your device. For personal emails this may be acceptable; for work or legal documents, it's a significant privacy and compliance concern.
macOS-Specific Options
macOS has no native support for .msg files. Options include:
- Outlook for Mac (the most complete solution)
- Third-party apps from the Mac App Store designed to read .msg files
- Converting the file to .eml format using a utility, then opening it in Apple Mail
Conversion tools exist specifically for .msg → .eml transformation and tend to preserve core content reliably, though some metadata or formatting may be simplified.
Opening .msg Files on Mobile Devices
Neither iOS nor Android can natively open .msg files. The Microsoft Outlook mobile app, however, does support .msg files as attachments — so if you receive a .msg file within Outlook Mobile, tapping it will open it directly.
Outside of Outlook Mobile, options are limited. Some file manager apps claim .msg support, but rendering quality varies widely and complex emails often display incorrectly.
Key Variables That Affect Which Method Works for You
| Factor | Why It Matters |
|---|---|
| Operating system | Windows has the most native support options; macOS and Linux require workarounds |
| Whether you have Outlook | Determines if the simplest path is available |
| File sensitivity | Affects whether a web-based viewer is acceptable |
| File complexity | Rich HTML, embedded images, or nested attachments may not render in basic viewers |
| Frequency of need | One-off viewing vs. regular workflow changes which solution makes sense |
| Technical comfort level | Some tools require add-ons, command-line steps, or manual file association |
Why the Format Exists (And Why This Problem Keeps Coming Up)
The .msg format was designed for Outlook's internal ecosystem, not cross-platform sharing. It solved a real problem — preserving the complete state of an email for archiving or legal discovery — but it was never intended to be a universal format like PDF.
Organizations that use Outlook heavily often send .msg files without realizing the recipient may not have compatible software. Legal firms, large enterprises, and government agencies are particularly common sources of .msg files, since email archiving and eDiscovery workflows routinely produce them.
The format also matters in IT and compliance contexts: .msg files can store email metadata that .eml conversions sometimes strip, which is why original .msg files are often legally or procedurally significant.
What Determines the Right Approach
Whether Outlook makes sense, a lightweight viewer is sufficient, a conversion workflow fits better, or a web tool is acceptable depends on how often you encounter .msg files, what platform you're on, how sensitive the content is, and whether preserving every formatting detail actually matters for your use case. Those specifics are yours to weigh.