Which email file formats can I open?

You can open standard MIME .eml files, Microsoft Outlook binary .msg files, and Unix / Thunderbird / Google Takeout .mbox mailbox archives.

Does this tool load remote images or notify the sender?

No. Remote image loading and tracking pixels are blocked by default. The site operates under a strict connect-src none Content Security Policy, meaning network requests are completely forbidden by your browser.

Can I extract attachments from Outlook MSG files?

Yes. Both regular file attachments and inline embedded images are extracted and available for instant local download.

Is there any file size limit for mbox archives?

Mbox archives up to 100 MB can be processed smoothly in standard browser memory. For giant multi-gigabyte archives, consider splitting or filtering the mailbox prior to reading.

Are my emails or attachments stored on any server?

Never. All parsing and rendering take place in-memory on your local device. Once you close or reload the browser tab, all memory is immediately freed.

Offline email reader

Private In-Browser Email Inspection

Email documents (.eml, .msg, .mbox) are decoded entirely inside your browser. No message contents, header addresses, or attachments are uploaded. Remote tracking pixels and external images are automatically blocked so senders cannot track when or where you opened the message.

Note: Interactive web forms, scripts, and embedded frames inside HTML messages are sanitized and neutralized for security.

Select Email Message File

Drop your EML, MSG, or mbox file here, or browse

Supports .eml, .msg (Outlook), and .mbox up to 50 MB. 100% private in-browser decoding.

About this offline email reader

Open, inspect, and extract attachments from EML, Outlook MSG, and Mbox files directly in your browser without uploading to any remote mail server. View full RFC 822 email headers, toggle between formatted HTML and plain text bodies, sanitize tracking pixels, and download attachments with cryptographic safety.

Email files contain confidential correspondence, sensitive business negotiations, financial statements, and private personal data. Conventional cloud webmail viewers force you to upload these messages to third-party servers, exposing sender metadata, message contents, and unencrypted attachments. Our offline email reader processes every message locally inside your browser memory using sandboxed parsing engines. It inspects RFC 822 MIME headers, strips remote tracking beacons and scripts, renders multipart layouts safely, and extracts attached documents with complete zero-knowledge isolation.

Runs in this tab — no uploadFree, no account, no watermark

Step by step

1Open or drop your email fileSelect an .eml, .msg, or .mbox file up to 100 MB directly from your device storage, or drag and drop it into the designated drop zone. The file is read into memory instantly without any network upload.
2Select message from archiveIf viewing an mbox archive containing multiple messages, select an email from the message list index to inspect its individual headers, content, and attachments.
3Inspect verified email headersReview authenticated envelope details including From, To, CC, BCC, Date, Subject, Message-ID, Reply-To, and raw MIME headers to verify message provenance and transit hops.
4Toggle view and download attachmentsSwitch between sanitized HTML view and raw plain text. Preview inline images and click any attachment badge to download extracted files directly to your device.

RFC 822 and Outlook MSG format support

Email messages exist in several standard and proprietary file formats depending on the sending client and backup utility. Standard EML files follow RFC 822 and RFC 2822 MIME structure, packing headers, boundary-delimited message bodies, and base64-encoded attachments into plain text streams. Outlook MSG files, by contrast, use Microsoft Compound File Binary Format (CFBF) with OLE structured storage streams for properties, recipients, and attachments. This tool includes specialized in-browser parsers for both standard MIME and binary OLE MSG files, extracting headers, rich bodies, and attachments accurately without requiring Microsoft Outlook or cloud conversion services.

Privacy-first HTML sanitization and tracker blocking

Marketing emails and newsletters frequently embed invisible tracking pixels (1x1 transparent images) and remote CSS resources to monitor when, where, and how often you open a message. Furthermore, unvetted HTML emails may carry dangerous active scripts or frame embeds. Our reader applies strict client-side DOMPurify-based sanitization that completely eliminates script tags, object embeds, frames, and inline event handlers. Crucially, all remote HTTP and HTTPS image URLs are blocked by default from loading, preventing tracking beacons from notifying the sender. Local inline image attachments referenced via cid: URLs are safely translated into isolated object URLs in memory.

Mbox multi-message mailbox archives

The mbox format is widely used by Unix mail systems, Mozilla Thunderbird, Google Takeout, and email migration utilities to store entire folders of messages in a single continuous file. Messages are delimited by From lines at the beginning of each email. Our parser scans mbox streams, partitions individual messages accurately, extracts header summaries, and presents an interactive message browser that lets you navigate through thousands of archived emails without external database servers or desktop email clients.

Direct attachment extraction and verification

Email attachments often contain contracts, invoices, spreadsheets, and archives. When opening an email in this reader, all MIME multipart attachments are identified, decoded from base64 or quoted-printable encodings, and verified. Each attachment displays its original filename, MIME content type, and human-readable byte size. You can download individual attachments directly to your filesystem with a single click, without risking exposure to external servers or malicious payload execution.

Zero upload security guarantee

Every response from this site is served with a Content Security Policy whose connect-src directive is set to none. That is not a promise in marketing copy; it is an instruction to your browser, and the browser is the one enforcing it. While this page is open it cannot open a connection to anywhere — not to this site, not to anyone else — so there is no path by which your document could be uploaded, not by a bug, not by a future change, not by a script that should not be here. e2e/egress-proof.spec.ts asserts the served header and then tries to send data out by every route a page has and requires each attempt to be refused, and it runs on every build.

The second half of the guarantee is that the code has nowhere to send anything from. lib/tools/local-source-policy.test.ts reads every source file under lib/tools, workers, components and app on every test run and fails the build if any of them contains fetch, XMLHttpRequest, WebSocket, EventSource, sendBeacon or a peer connection, or even a remote address written down in a comment. A tool here cannot acquire an upload by accident, because the file that would have to contain one cannot be committed.

Client-side processing limits

Computations run directly on your own device using WebAssembly, Web Workers, and modern browser APIs including Web Crypto and TextDecoder. There are no server queues, no background telemetry, and no temporary cloud files created. Large operations remain responsive by offloading heavy parsing and conversion tasks to dedicated worker threads, ensuring the browser UI never freezes during intensive document and data processing tasks.

Questions people ask

Which email file formats can I open?: You can open standard MIME .eml files, Microsoft Outlook binary .msg files, and Unix / Thunderbird / Google Takeout .mbox mailbox archives.
Does this tool load remote images or notify the sender?: No. Remote image loading and tracking pixels are blocked by default. The site operates under a strict connect-src none Content Security Policy, meaning network requests are completely forbidden by your browser.
Can I extract attachments from Outlook MSG files?: Yes. Both regular file attachments and inline embedded images are extracted and available for instant local download.
Is there any file size limit for mbox archives?: Mbox archives up to 100 MB can be processed smoothly in standard browser memory. For giant multi-gigabyte archives, consider splitting or filtering the mailbox prior to reading.
Are my emails or attachments stored on any server?: Never. All parsing and rendering take place in-memory on your local device. Once you close or reload the browser tab, all memory is immediately freed.