esp-idf-smtp 0.4.0

Lightweight SMTP client over esp_tls for esp-idf-svc in Rust
# Contributing

Contributions are welcome! By submitting a pull request, you agree to the terms
below.

## Contributor License Agreement (CLA)

This project requires a CLA for all contributions. When you open your first pull
request, the CLA Assistant bot will comment with a link to review and sign the
agreement. You only need to sign once — it covers all future contributions to
this repository.

**Why?** The CLA ensures the project maintainer retains the ability to offer the
code under alternative licensing terms (e.g., a commercial license) without
needing to track down every contributor individually. Your contribution remains
publicly available under the project's open-source license (MPL-2.0) regardless.

## How to contribute

1. Fork the repository
2. Create a feature branch from `main`
3. Make your changes
4. Ensure tests pass (if applicable)
5. Open a pull request with a clear description of the change

## Code of conduct

Be respectful. Contributions are evaluated on technical merit.