Summary
This server wraps the MailDev email testing tool with MCP, giving you programmatic control over a Docker container running a local SMTP sink. You get tools to start and stop the container with configurable ports and auth, then inspect received emails through MailDev's REST API. The workflow is built for test automation: trigger your app to send mail, call WaitForEmail to poll until it arrives, then use GetEmail, SearchEmails, or GetEmailHtml to validate the result. You can also pull attachment content as base64 or run byte-by-byte verification against expected payloads. Useful when you're testing email flows locally and want your AI assistant to orchestrate the SMTP environment and assertion logic without manual Docker or API wrangling.
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MailDevMcp
English | 日本語
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
StartMaildevto launch a local MailDev container - Trigger your application to send an email
- Call
WaitForEmailif delivery is asynchronous - Use
ListEmails,SearchEmails, orGetEmailto inspect the result - Use
GetEmailHtml,GetAttachmentContent, orVerifyAttachmentwhen deeper validation is needed - Clean up with
DeleteEmail,DeleteAllEmails, orStopMaildev
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
GetEmailandListEmails- Render missing or empty subjects as
(no subject) - Render missing address lists as
(none)
- Render missing or empty subjects as
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
Featured
Keep your Mac awake while Claude Code and 40+ AI agents run. Sleeps when they're idle.
One time payment $9 →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →On Capafy, your Skill runs online 24/7 as an agent product, and you get paid every time someone uses it.
Start earning →Configuration
MAILDEV_API_PORTPort number for the MailDev REST API (default: 1080)
Categories
Registryactive
PackageMailDevMcp
TransportSTDIO
UpdatedMar 19, 2026
