Send Emails with Rust

# Cargo.toml
[dependencies]
reqwest = { version = "0.12", features = ["json"] }
serde_json = "1"
tokio = { version = "1", features = ["full"] }

use reqwest::Client;

let client = Client::new();
let api_key = "sk_live_...";

use reqwest::Client;
use serde_json::json;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let api_key = std::env::var("POSTSTACK_API_KEY")?;

    let response = Client::new()
        .post("https://api.poststack.dev/v1/emails")
        .header("Authorization", format!("Bearer {}", api_key))
        .json(&json!({
            "from": "hello@yourdomain.com",
            "to": "user@example.com",
            "subject": "Hello from Rust!",
            "html": "<h1>Welcome!</h1>"
        }))
        .send()
        .await?;

    println!("{}", response.text().await?);
    Ok(())
}