Lettermint Rust SDK

Official Rust SDK for the Lettermint sending and team APIs.

Requirements

• Current stable Rust. The crate's rust-version tracks the current supported stable minor release.
• Tokio or another async runtime compatible with reqwest

Installation

[dependencies]
lettermint = "0.1"
tokio = { version = "1", features = ["macros", "rt-multi-thread"] }

Send Email

use lettermint::Lettermint;

#[tokio::main]
async fn main() -> lettermint::Result<()> {
    let email = Lettermint::email(std::env::var("LETTERMINT_TOKEN").unwrap())?;

    let response = email
        .email()
        .from("sender@example.com")
        .to("recipient@example.com")
        .subject("Hello from Rust")
        .html("<p>Hello from Lettermint.</p>")
        .idempotency_key("welcome-123")
        .send()
        .await?;

    println!("{}", response.message_id);
    Ok(())
}

The fluent email builder owns its payload. Each call to email.email() starts with a fresh payload, so attachments, headers, metadata, and recipients do not leak between sends.

Direct API Payloads

use lettermint::{types, Lettermint};

#[tokio::main]
async fn main() -> lettermint::Result<()> {
    let email = Lettermint::email(std::env::var("LETTERMINT_TOKEN").unwrap())?;

    let payload = types::SendMailRequest {
        from: "sender@example.com".into(),
        to: vec!["recipient@example.com".into()],
        subject: "Typed payload".into(),
        text: Some("Hello from Lettermint.".into()),
        ..Default::default()
    };

    email.send(&payload).await?;
    Ok(())
}

Team API

use lettermint::Lettermint;

#[tokio::main]
async fn main() -> lettermint::Result<()> {
    let api = Lettermint::api(std::env::var("LETTERMINT_TEAM_TOKEN").unwrap())?;
    let domains = api.domains().list(&[("page[size]", "10")]).await?;

    for domain in domains.data {
        println!("{}", domain.domain);
    }

    Ok(())
}

Lettermint::email(...) authenticates with X-Lettermint-Token for sending endpoints. Lettermint::api(...) authenticates with Authorization: Bearer ... for team endpoints.

Webhooks

use lettermint::Webhook;

fn handle(payload: &str, signature: &str, delivery: i64) -> lettermint::Result<serde_json::Value> {
    Webhook::new(std::env::var("LETTERMINT_WEBHOOK_SECRET").unwrap())
        .verify(payload, signature, Some(delivery))
}

Webhook verification checks the t=... timestamp, validates the v1=... HMAC-SHA256 signature in constant time, cross-checks the optional delivery timestamp, and enforces a 5 minute tolerance by default.

Development

cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test --all-features --locked

Generated DTOs live in src/types.rs. Regenerate them from the repository root with:

python3 sdk-generator/rust/generate-types.py