MSG Inspector
A free, browser-based Outlook MSG file analyzer. Drop any .msg file to instantly inspect its transport headers, authentication results, body, attachments, and raw MSG properties — no Outlook required and nothing uploaded to a server.
MSG Inspector
Analyze Outlook .msg files instantly — headers, security, attachments, and more. All processing happens in your browser.
Drop your .msg file or click to browse
Supports .msg files — processed 100% in your browser
How to use MSG Inspector
- 1 Save an email from Outlook as a .msg file: right-click the message in Outlook and choose "Save As", then select Outlook Message Format.
- 2 Open MSG Inspector and drag the .msg file onto the upload area, or click to browse.
- 3 The tool decodes the Compound File Binary Format (CFBF) entirely in your browser and displays the results in tabs.
- 4 Use the Headers tab to view transport headers decoded from the MSG property set, including routing and timestamps.
- 5 Check the Security tab to see SPF, DKIM, and DMARC authentication results extracted from the transport headers.
- 6 Download any embedded attachments from the Attachments tab, and inspect raw MSG properties in the Properties tab.
Features
Who uses MSG Inspector?
Security analysts and incident responders use it to examine suspicious Outlook emails during phishing investigations. Because MSG files are parsed entirely in the browser, even potentially malicious messages can be analyzed safely without opening them in Outlook.
IT helpdesk and email administrators use it to decode transport headers from Outlook-sourced emails and diagnose delivery issues, authentication failures, and routing anomalies in Exchange or Microsoft 365 environments.
Legal and compliance teams use it to review exported Outlook emails during eDiscovery without requiring a licensed copy of Outlook on every reviewer's machine.
Developers working on email integrations use it to inspect the raw MAPI property store and verify that their outgoing Outlook messages contain the expected metadata.
Frequently asked questions
What is an MSG file?
An MSG file is the native email format used by Microsoft Outlook. It is based on the Compound File Binary Format (CFBF), a Microsoft-specific container format that stores the email body, headers, attachments, and metadata as a structured property set called MAPI (Messaging Application Programming Interface). Unlike EML files, MSG files require specialized parsing and are not human-readable as plain text.
Do I need Outlook to open a .msg file?
No. MSG Inspector parses Outlook .msg files directly in your browser using the open-source @kenjiuno/msgreader library. You do not need Outlook, Windows, or any other software installed. It works in any modern browser on any operating system.
Is MSG Inspector free and private?
Yes. MSG Inspector is completely free to use with no sign-up required. The .msg file is parsed in your browser and never transmitted to any server. This makes it safe to use for analyzing sensitive corporate emails, suspected phishing messages, or confidential communications.
Can I extract attachments from a .msg file?
Yes. MSG Inspector lists all attachments embedded in the .msg file — including nested MSG attachments — along with their filenames, MIME types, and file sizes. You can download each attachment individually for further analysis.
How is MSG Inspector different from EML Inspector?
EML files use the open MIME RFC 822 plain-text format and are supported by most mail clients. MSG files use a proprietary Microsoft binary format specific to Outlook. MSG Inspector decodes the binary CFBF container, while EML Inspector parses standard MIME. If you have an email from Outlook, use MSG Inspector. For emails from Gmail, Apple Mail, or Thunderbird, use EML Inspector.