Java-MCP-Server-For-SMTP-Mailing
Provides an MCP server (Java 21) that exposes an email-sending capability via an MCP tool named `send-email` and also offers REST endpoints for testing (e.g., POST `/api/test-email`) and health checks. Supports multiple transports for MCP clients (STDIO, SSE, and Streamable HTTP) and forwards email delivery to an SMTP server (Gmail SMTP supported with TLS/app passwords per the README).
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Security depends heavily on deployment. README indicates SMTP TLS is configurable and Gmail app passwords are used, which is better than plain passwords, but the instructions show SMTP credentials hard-coded in `Application.java` (weak secret handling). No endpoint-level authentication/authorization or anti-abuse controls are described for the REST/MCP interfaces, so the server could be abused if exposed. Dependency hygiene is not assessable from the provided README/repo metadata alone. TLS is likely used for SMTP if configured (e.g., port 587 with STARTTLS), but there is no clear enforcement statement for all cases.
⚡ Reliability
Best When
You need a locally hosted MCP server that bridges an MCP client (e.g., Claude Desktop) to an SMTP provider for controlled, low-volume notifications/testing.
Avoid When
You require first-class enterprise auth (OAuth) and fine-grained authorization, strong anti-abuse controls, or fully documented API contracts beyond the README.
Use Cases
- • Integrate AI/MCP assistants with email sending workflows
- • Programmatically send transactional notifications (e.g., reminders, completion emails) from MCP-capable clients
- • Local testing of MCP tool behavior via a REST endpoint
- • Send emails through different SMTP providers using the same MCP interface
Not For
- • Production email delivery without additional hardening (credential management, abuse prevention, input validation, observability)
- • Bulk/spam email sending or any workflow requiring strong deliverability controls not described in the README
- • Environments that cannot expose SMTP credentials or cannot run outbound SMTP connections
Interface
Authentication
The README instructs embedding SMTP credentials in `Application.java`. No authorization mechanism (API keys, OAuth, IAM, or scopes) for calling the MCP server or REST endpoints is described.
Pricing
Self-hosted open-source project; costs depend on your SMTP provider (e.g., Gmail app password) and infrastructure.
Agent Metadata
Known Gotchas
- ⚠ No documented auth for HTTP endpoints; ensure your environment is trusted or place it behind a firewall/reverse proxy.
- ⚠ Because credentials appear configured in code per README, agents must be careful not to leak secrets and should prefer environment-variable/config injection if available in the project code.
- ⚠ Email-sending operations are side-effecting; agents should avoid repeated calls unless the tool/reporting is designed to be safe.
- ⚠ Transport selection matters (`--stdio`, `--sse`, `--streamable-http`); wrong transport arguments may cause connection failures.
Alternatives
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Scores are editorial opinions as of 2026-04-04.