simple_smtp_sender

A Simple SMTP Email sender crate with the support of sync or async sending. Can be called from Python. Powered by Rust, lettre and PyO3.

Overview

This project provides rust crate and a Python extension module implemented in Rust for sending emails via SMTP, including support for attachments, CC, and BCC. There are methods for both synchronous and asynchronous sending. It leverages the performance and safety of Rust, exposes a convenient Python API, and is built using PyO3 and lettre. The python module is compatible with Python 3.10 and above.

Features

Send emails via SMTP synchronously or asynchronously
Support HTML email contents
Attach files to emails
Support for CC and BCC
Secure authentication
Easy configuration via Python class
Flexible feature flags for Rust-only or Python-enabled builds
No Python dependencies required for Rust-only usage

Installation

Python Package from PyPI

uv pip install simple_smtp_sender
# or
pip install simple_smtp_sender

Rust Crate

[dependencies]
# Rust-only version (no Python dependencies)
simple_smtp_sender = { version = "0.4.1" }

Build Python package from Source (requires Rust toolchain and maturin)

Please note that the default feature does not include the Python PyO3 binding. To build Python binding using maturin, please declare the dependency with --features python:

git clone https://github.com/guangyu-he/simple_smtp_sender.git
cd simple_smtp_sender
## prepare venv and maturin if needed
# uv venv
# uv sync
uv run maturin develop --features python

Or build a wheel:

uv run maturin build --features python
pip install target/wheels/simple_smtp_sender-*.whl

Requirements

Python >= 3.10 (for Python package)
Rust toolchain (for building from source)

Usage

Rust

check examples.rs in examples/ for more examples.

Python

An example from Python API:

from simple_smtp_sender import EmailConfig, send_email, async_send_email

config = EmailConfig(
    server="smtp.example.com",
    sender_email="your@email.com",
    username="your_username",
    password="your_password",
)

# Synchronous send (blocking)
send_email(
    config,
    recipient=["recipient@email.com"],
    subject="Test Email",
    body="Hello from Rust!",
)

# With attachment, CC, and BCC:
send_email(
    config,
    recipient=["recipient@email.com"],
    subject="With Attachment",
    body="See attached file.",
    cc=["cc@email.com"],
    bcc=["bcc@email.com"],
    attachment="/path/to/file.pdf",
)

# Asynchronous send (non-blocking)
import asyncio


async def main():
    await async_send_email(
        config,
        recipient=["recipient@email.com"],
        subject="Async Email",
        body="Sent asynchronously!",
    )


asyncio.run(main())

API

`EmailConfig`

Configuration class for SMTP server and credentials.

__new__ parameters:

server: SMTP server URL
sender_email: Sender's email address
username: SMTP username
password: SMTP password

APIs:

load_from_env(): Load configuration from environment variables:
- EMAIL_SERVER
- EMAIL_SENDER_EMAIL
- EMAIL_USERNAME
- EMAIL_PASSWORD
load_from_map(config_map: dict): Load configuration from a dictionary.
load_from_pydantic(pydantic_obj: BaseModel): Load configuration from a Pydantic BaseModel. Requires pydantic to be installed in the active Python environment. Raises RuntimeError if pydantic cannot be imported, TypeError if the argument is not a BaseModel instance, and ValueError if the model's fields cannot be deserialized into an EmailConfig.
to_dict(): Convert the EmailConfig instance into a Python dict[str, str].

Sends an email synchronously (blocking) using the provided configuration.

send_email(config, recipient, subject, body, cc=None, bcc=None, attachment=None)

config: EmailConfig instance
recipient: List of recipient email(s)
subject: Email subject
body: Email body
cc: List of CC recipients (optional)
bcc: List of BCC recipients (optional)
attachment: Path to file to attach (optional)

Sends an email asynchronously (non-blocking, returns an awaitable).

async_send_email(config, recipient, subject, body, cc=None, bcc=None, attachment=None)

config: EmailConfig instance
recipient: List of recipient email(s)
subject: Email subject
body: Email body
cc: List of CC recipients (optional)
bcc: List of BCC recipients (optional)
attachment: Path to file to attach (optional)

Development

Rust dependencies are managed in Cargo.toml.
Python build configuration is in pyproject.toml.
Main Rust logic in src/.

License

MIT

simple_smtp_sender 0.4.1