MailDevMcp

mcp-name: io.github.pierre3/maildev-mcp

An MCP (Model Context Protocol) server for MailDev.
Manage MailDev Docker containers and inspect received emails directly from your AI-powered editor or MCP client.

This server is intended for local development and test automation scenarios where an MCP client needs to:

start or stop a MailDev container
inspect inbox contents
wait for emails after triggering application behavior
inspect HTML bodies and attachments
verify attachment integrity byte-for-byte

Installation

Install as a global .NET tool:

dotnet tool install -g MailDevMcp

After installation, the maildev-mcp command becomes available.

MCP Client Configuration

Add the following to your MCP client settings (e.g. Claude Desktop, VS Code, etc.):

{
  "mcpServers": {
    "maildev-mcp": {
      "command": "maildev-mcp",
      "env": {
        "MAILDEV_API_PORT": "1080"
      }
    }
  }
}

Environment Variables

Variable	Default	Description
`MAILDEV_API_PORT`	`1080`	Port number for the MailDev REST API

Typical Workflow

Call StartMaildev to launch a local MailDev container
Trigger your application to send an email
Call WaitForEmail if delivery is asynchronous
Use ListEmails, SearchEmails, or GetEmail to inspect the result
Use GetEmailHtml, GetAttachmentContent, or VerifyAttachment when deeper validation is needed
Clean up with DeleteEmail, DeleteAllEmails, or StopMaildev

Available Tools

Tool	Description
`StartMaildev`	Start the MailDev Docker container with configurable SMTP port, API port, authentication, and TLS
`StopMaildev`	Stop and remove the MailDev Docker container
`MaildevStatus`	Check the running status of MailDev
`ListEmails`	Retrieve the list of received emails
`GetEmail`	Get the details of an email by ID, including attachment information
`GetEmailHtml`	Get the HTML body of an email by ID
`SearchEmails`	Search received emails by subject, sender, or recipient
`DeleteEmail`	Delete a single email by ID
`DeleteAllEmails`	Delete all received emails
`WaitForEmail`	Wait until a new email matching given criteria arrives (useful for test automation)
`GetAttachmentContent`	Get the raw Base64-encoded content of an email attachment
`VerifyAttachment`	Verify that an email attachment matches the original data by byte-by-byte comparison

Tool Behavior Notes

StartMaildev
- Supports custom SMTP and API ports
- Supports optional SMTP authentication
- Treats empty or whitespace-only credentials as authentication disabled
- Supports TLS with a generated self-signed certificate
GetEmail and ListEmails
- Render missing or empty subjects as (no subject)
- Render missing address lists as (none)
WaitForEmail
- Polls MailDev until a matching email arrives or the timeout is reached
- Reports transient MailDev connection failures in the returned message when they occur during polling
VerifyAttachment
- Accepts a Base64-encoded original payload
- Compares the received attachment byte-by-byte
- Reports either exact match, size mismatch, or content mismatch

Requirements and Assumptions

Docker must be installed and available on the same machine where this MCP server runs
MailDev is accessed through its HTTP API on localhost
The configured API port in the MCP client must match the MailDev API port exposed by Docker

Prerequisites

.NET 10 SDK or later
Docker (for running the MailDev container)

Building from Source

git clone https://github.com/pierre3/MailDevMcp.git
cd MailDevMcp
dotnet pack -c Release
dotnet tool install -g --add-source ./bin/Release MailDevMcp

License

MIT

maildev-mcp