Rust

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

use serde::{Deserialize, Serialize};

#[derive(Serialize)]
struct SendEmail {
    from: String,
    to: Vec<String>,
    subject: String,
    html: Option<String>,
}

#[derive(Deserialize)]
struct EmailResponse {
    id: String,
}

#[tokio::main]
async fn main() -> Result<(), reqwest::Error> {
    let client = reqwest::Client::new();

    let email = SendEmail {
        from: "you@yourdomain.com".into(),
        to: vec!["user@example.com".into()],
        subject: "Hello from Sendi".into(),
        html: Some("<p>It just works.</p>".into()),
    };

    let res: EmailResponse = client
        .post("https://app.usesendi.com/api/emails")
        .header("Authorization", "Bearer snd_your_api_key")
        .json(&email)
        .send()
        .await?
        .json()
        .await?;

    println!("Sent: {}", res.id);
    Ok(())
}