What Are .msg Files?
When you drag an email from the Outlook desktop application to another location – a folder, the desktop, or a browser window – Windows saves it as a .msg file. This is Microsoft’s proprietary email format and contains the complete message: all header fields (From, To, CC, BCC, Subject, Date) and the full message body in both plain text and HTML.
The Email Extractor reads .msg files entirely in your browser using JavaScript. No data is ever uploaded to a server.
What Gets Extracted?
The extractor reads the structured fields of each .msg file and applies email pattern matching to all of them:
| Field | Description | Extracted |
|---|---|---|
| From | Sender’s email address | ✓ Yes |
| To | Primary recipients | ✓ Yes |
| CC | Carbon copy recipients | ✓ Yes |
| BCC | Blind copy (if present in the file) | ✓ Yes |
| Body | Plain text and HTML body content | ✓ Yes |
Duplicates are removed automatically. If you process multiple .msg files, the results are merged with any previously extracted addresses.
Method 1: Drag & Drop from Outlook (Fastest)
This is the most direct method – no saving or exporting required.
Method 2: Save as .msg and Upload
If drag & drop does not work in your environment (e.g. due to browser or OS security policies), save the emails first:
- In Outlook, select the email(s) you want to process.
- Drag them to your Desktop or a folder – Outlook saves each as a
.msgfile. - On the Email Extractor, click Upload File(s) and select the saved
.msgfiles. Multiple files are supported. - Results are extracted and displayed immediately – no extra click required.
Processing Multiple Emails at Once
Both methods support batch processing. You can select dozens or even hundreds of emails in Outlook and drag them all at once. Each .msg file is processed individually and the addresses are merged into a single deduplicated result list.
Tip: Use Outlook’s search and filter features to narrow down the emails before selecting – for example, filter by sender domain, date range, or folder to get exactly the addresses you need.
Use Cases
Building Mailing Lists from Correspondence
Select all emails from a specific sender or folder and drag them in. Every person who was part of those conversations – senders, recipients, CC’d contacts – appears in your result list ready to export.
Event Follow-Up
After a conference or event, select all emails received from attendees and extract their addresses in one step. Filter by domain afterward to segment by company or provider.
Supplier or Partner Contact Lists
Process incoming emails from a supplier folder to compile a current contact list. The tool automatically deduplicates, so each address appears only once regardless of how many emails a contact sent.
Migration and CRM Import
Extract addresses from archived email folders to import contacts into a new CRM or mailing platform. Export the results as .csv for direct import.
Technical Background
The .msg format is based on the Compound File Binary Format (also known as OLE2 or Structured Storage), a container format developed by Microsoft. It stores message properties – including all header fields and body content – as named streams within a binary container.
The Email Extractor parses these files in your browser using the open-source msgreader library (@kenjiuno/msgreader), loaded on demand from the esm.sh CDN. The library extracts structured fields (sender, recipients) as well as body text. The email regex is then applied to all fields to catch any additional addresses mentioned in the body.
Because all parsing happens locally in your browser, your email content is never transmitted to any server. This makes the tool safe even for confidential or internal correspondence.
Ready to Extract?
Open the Email Extractor and drag your Outlook emails directly onto the page.
Open Email Extractor