resendmailer is a lightweight command-line utility for relaying RFC822-compliant email messages via the Resend API. It's designed to be simple, scriptable, and easy to integrate into automation pipelines or backend tooling.

  • 📦 Precompiled executables for Windows and Linux
  • 📥 Accepts input from stdin or a file
  • 🪵 Optional diagnostic logging
  • 🔑 Supports CLI flag, environment variable, or .env file for API key

📥 Download

No build required! Grab the precompiled binary for your platform:

Platform Architecture Download
Windows x64 resendmailer-windows.exe
Linux x64 resendmailer-linux-x64
Linux ARM64 resendmailer-linux-arm64

Quick install (Linux)

# x64
curl -fLo /usr/local/bin/resendmailer https://fossil.klutch.software/resendmailer/uv/resendmailer-linux-x64
chmod +x /usr/local/bin/resendmailer

# ARM64
curl -fLo /usr/local/bin/resendmailer https://fossil.klutch.software/resendmailer/uv/resendmailer-linux-arm64
chmod +x /usr/local/bin/resendmailer

Quick install (Windows / PowerShell)

Invoke-WebRequest -Uri https://fossil.klutch.software/resendmailer/uv/resendmailer-windows.exe -OutFile resendmailer.exe

Verify

resendmailer --help

🛠️ Usage

You can use resendmailer in two main ways:

1. From a File

resendmailer --file ./message.txt --apiKey re_xxxxxxxxx

2. From Standard Input

cat ./message.txt | resendmailer --apiKey re_xxxxxxxxx

3. API Key Configuration

The API key is resolved in this order:

  1. --apiKey CLI flag (not recommended for production — visible in process listings)
  2. $RESEND_API_KEY environment variable
  3. RESEND_API_KEY in a .env file in the current directory

Copy the included .env.example to get started:

cp .env.example .env
# Edit .env and replace re_your_key_here with your actual key

Optional flags

  • --log /path/to/log.json — Save structured logs (JSON) for diagnostics.

🧪 Development

To build the CLI from source:

  1. Ensure Dart SDK 3.8+ is installed
  2. Clone the repo and run:
dart pub get
dart analyze
dart test
dart compile exe ./bin/resendmailer.dart -o ./build/resendmailer.exe

Or use the included Taskfile.dev to cross-compile:

task compile

This will output executables to ./build/.

💌 Contributing

Contributions are welcome, though note that this project uses Fossil SCM instead of Git.

As many are unfamiliar with fossil, please read our CONTRIBUTING instructions.

To clone the project:

fossil clone https://fossil.klutch.software/resendmailer resendmailer.fossil
fossil open resendmailer.fossil

🔐 License

MIT License. See LICENSE file or visit opensource.org/licenses/MIT.

🌐 Project Homepage

Repository: https://fossil.klutch.software/resendmailer