Mail Viewer MCP Server

A Model Context Protocol server that lets Claude, Cursor, Cline, and any MCP-compatible AI agent read, convert, and extract attachments from email files — .eml, .msg, .p7m, .mim, .tnef, .vcf, .olk15, and more.

The server is built into CoolUtils Mail Viewer — there is nothing extra to install. Run MailViewer.exe --mcp and the program skips its GUI to act as a stdio JSON-RPC server.

What you can do

Once connected, give your AI assistant natural-language instructions:

"Convert all .msg files in D:\archive to PDF and put them in D:\output" — the agent calls convert_mail on each file.
"What attachments does this EML have and who sent it?" — get_mail_info returns a clean JSON object instantly.
"Extract all attachments from these 40 emails into C:\attachments" — extract_attachments saves them all in one pass.

Everything runs locally — your mail files are never uploaded anywhere.

Tools

`convert_mail`

Converts a mail file to the specified output format using the full Mail Viewer rendering engine.

Source formats: .eml, .msg, .mim, .p7m, .vmbx, .tnef, .mapixml, .olk15, .vcf, .contact, .3uc
Output formats: pdf, html, txt, doc, rtf, tiff, jpg, png, bmp, emf, eml, xps

PDF and DOCX output preserves embedded HTML, inline images, attachment previews, and message headers — identical to what you see in the GUI.

`get_mail_info`

Reads a mail file and returns its metadata as JSON: sender, To/CC/BCC recipients, subject, date, raw RFC headers, plain-text and HTML body, and a list of attachments with names, sizes, and content types. The source file is not modified.

`extract_attachments`

Saves all attachments from a mail file into a target folder (created automatically if it does not exist). Returns the list of saved files with absolute paths and sizes in bytes.

Full input/output schemas: schemas/mcp-tools.json.

Example sessions

See examples/usage.md for end-to-end transcripts:

Batch convert a folder — point Claude at a directory of .msg files and ask for PDFs.
Forensic triage — ask Claude to summarize sender/subject/attachment patterns across 100 emails.
Attachment harvesting — extract every attachment from a quarter's worth of legal correspondence into one folder.

Technical details

Transport: stdio (NDJSON, one JSON-RPC 2.0 message per line, UTF-8)
Protocol version: 2024-11-05
Server name (reported in initialize): mailviewer-mcp
Platform: Windows 7 / 8 / 10 / 11
License: Commercial (Mail Viewer); MIT (this configuration/docs repo). Personal license starts at $49.90, 30-day free trial.

Server manifest: schemas/mcp-server.json.

Resources

Installation

1. Install Mail Viewer

Download and install CoolUtils Mail Viewer for Windows from https://www.coolutils.com/MailViewer. The MCP server is bundled inside the standard MailViewer.exe binary — no extra package, no separate license.

A 30-day free trial is available; no email or credit card is required.

2. Configure your MCP client

Claude Code

Add to ~/.claude.json under mcpServers:

{
  "mcpServers": {
    "mailviewer": {
      "command": "C:\\Program Files\\CoolUtils\\CoolUtils Mail Viewer\\MailViewer.exe",
      "args": ["--mcp"]
    }
  }
}

Claude Desktop

Add to %APPDATA%\Claude\claude_desktop_config.json under mcpServers (same block as above).

Cursor

Add to .cursor/mcp.json in your project, or to ~/.cursor/mcp.json globally — same JSON block.

Cline

Open Cline's MCP settings UI and paste the same block.

A copy-paste-ready snippet is also installed alongside the executable as claude-config-snippet.json. Adjust the path if you installed Mail Viewer in a non-default location.

3. Verify

Run this in a command prompt to confirm the server responds:

echo {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"t","version":"0"}}} | "C:\Program Files\CoolUtils\CoolUtils Mail Viewer\MailViewer.exe" --mcp

You should see a single JSON-RPC response containing protocolVersion, serverInfo, and a tools capability.

Troubleshooting

The server doesn't respond. Verify the executable path is correct. The default install path on Windows is C:\Program Files\CoolUtils\CoolUtils Mail Viewer\MailViewer.exe. On 32-bit installs use C:\Program Files (x86)\….

Claude can't find the tools. Restart your MCP client after editing the config file. Check the client logs — for Claude Desktop, see %APPDATA%\Claude\logs.

File path errors. Use absolute paths in your prompts. Forward slashes (/) and backslashes (\) both work; quote paths with spaces.

Trial expired. Buy a license — Personal starts at $49.90. The MCP server keeps working in the same binary.

Licensed under MIT— you can use, modify, and redistribute it under that license's terms.

License

The configuration files, schemas, and documentation in this repository are released under the MIT License. CoolUtils Mail Viewer itself is commercial software — see the product page for licensing.