go-mapi

go-mapi brings "Send to → Mail recipient" to Gmail and Google Workspace users on Windows.

Right-click any file in Windows Explorer, click "Send to → Mail recipient", and the email appears ready to send in Gmail - no configuration needed, no subscription fees, completely open source.

THE PROBLEM

Windows has a built-in email feature called MAPI (Messaging Application Programming Interface) that lets any program send emails through your default email client. This powers:

• "Send to → Mail recipient" in Windows Explorer • "Email" buttons in PDF readers, Office apps, and thousands of Windows programs • Print-to-PDF-and-email workflows • Document sharing from any application

Gmail and Google Workspace have never supported MAPI. If Gmail is your email provider, these features simply don't work.

Third-party tools like Affixa filled this gap for years, but Affixa shut down in 2024, leaving Google Workspace users with no native solution.

go-mapi is the free, open-source replacement.

WHAT MAKES GO-MAPI DIFFERENT

✓ Free & Open Source - No subscription fees, no paid tiers, no feature locks ✓ Privacy-First - Data stays on your computer until you send; no third-party servers ✓ Simple Setup - Install extension + run one PowerShell command; works immediately ✓ Enterprise-Ready - Deployable via Group Policy and Chrome Enterprise Policy ✓ Active Development - Open source on GitHub with regular updates

KEY FEATURES

• Windows Integration: Makes Gmail your default MAPI email client • Right-Click Sending: "Send to → Mail recipient" from Windows Explorer • Application Support: Works with any Windows app that uses MAPI • Attachment Support: Send files of any size (up to Gmail's limits) • Draft or Send: Save emails as Gmail drafts to edit later, or send immediately • UTF-8 Support: Handles international characters correctly • Notifications: Desktop alerts when new emails are ready • Chrome & Edge: Works in both browsers

HOW IT WORKS

go-mapi uses a three-part architecture designed for security and simplicity:

1. MAPI Interceptor (DLL) - Captures email requests from Windows applications
2. Native Messaging Host (Local Service) - Watches for new emails and sends them to the browser
3. Browser Extension (This Extension) - Displays emails and uses Gmail API to send

All data stays on your local machine until you explicitly send the email. No third-party servers, no data collection.

SETUP INSTRUCTIONS

Step 1: Install This Extension Click "Add to Chrome" above.

Step 2: Copy Your Extension ID

1. Go to chrome://extensions/
2. Enable "Developer mode" (toggle in top-right)
3. Find "go-mapi" and copy the ID (long string of letters)

Step 3: Run the Installer Open PowerShell as Administrator and run:

irm https://raw.githubusercontent.com/marcfargas/go-mapi/main/scripts/install.ps1 | iex

When prompted, paste your extension ID.

Step 4: Test It

1. Right-click any file in Windows Explorer
2. Select "Send to → Mail recipient"
3. The go-mapi popup opens with the file attached
4. Click "Save as Draft" or "Send Now"

That's it! Any Windows program that supports email will now use Gmail.

PRIVACY & SECURITY

What data does go-mapi collect? None. go-mapi is 100% local. Email data is stored temporarily in your Windows temp folder and deleted after processing. No analytics, no telemetry, no tracking, no external servers except Gmail API (only when you send).

What permissions does the extension need? • nativeMessaging - Communicate with the local service • identity - Sign in to Google via Chrome's OAuth • storage - Save your preferences • notifications - Desktop alerts • Gmail API access - Send emails you approve

Can go-mapi access my existing emails? No. The extension only requests gmail.compose and gmail.send scopes. It cannot read your inbox or existing messages.

REQUIREMENTS

• Windows 10 or 11 • Google Chrome or Microsoft Edge • Gmail or Google Workspace account • Administrator access for initial installation

ENTERPRISE DEPLOYMENT

Deploy binaries via MSI/SCCM, force-install extension via Chrome Enterprise Policy, export registry keys for GPO. See GitHub for full deployment guide.

SUPPORT

• GitHub: https://github.com/marcfargas/go-mapi • Issues: https://github.com/marcfargas/go-mapi/issues • Discussions: https://github.com/marcfargas/go-mapi/discussions

TROUBLESHOOTING

Extension popup doesn't show emails: • Check Native Host is installed: C:\Program Files\go-mapi\go-mapi-host.exe • Verify extension ID matches in chrome://extensions/ • Restart Chrome/Edge after installation • Check for files in %TEMP%\go-mapi\

"Send to → Mail recipient" doesn't work: • Verify DLL is installed: C:\Program Files\go-mapi\go-mapi.dll • Re-run installer with -Force flag • Restart Windows

Open an issue on GitHub if you need help.

LICENSE

go-mapi is licensed under GPLv3. Free to use, modify, and distribute. You must share modifications under the same license.

CONTRIBUTING

We welcome bug reports, feature requests, code contributions, and documentation improvements. Visit the GitHub repository to get started.

Built with C++ (MinGW), Go, React, and TypeScript.