smtp-tls-client.rs

use lettre::transport::smtp::SmtpTransport;
use lettre::{
    message::Message,
    transport::smtp::{
        authentication::Credentials,
        client::{Certificate, Tls, TlsParameters},
    },
    Transport,
};

fn main() {
    // Create the email message
    let email = Message::builder()
        .from("[email protected]".parse().unwrap())
        .to("[email protected]".parse().unwrap())
        .subject("Hello from Rust!")
        .body(String::from(
            "This is a test email sent using Rust with STARTTLS.",
        ))
        .unwrap();

    let cert =
        Certificate::from_pem(&std::fs::read("./smtp.crt").unwrap())
            .unwrap();

    println!("cert: {:?}", cert);
    let tls_parameters = TlsParameters::builder("smtp.example.com".into())
        .add_root_certificate(cert)
//        .dangerous_accept_invalid_certs(true)
        .build()
        .unwrap();

    // SMTP credentials
    let creds = Credentials::new(
        "[email protected]".to_string(),
        "your-password".to_string(),
    );

    // Create the SMTP transport with STARTTLS
    let mailer = SmtpTransport::builder_dangerous("smtp.example.com")
        .port(1025)
        .tls(Tls::Required(tls_parameters))
        .credentials(creds)
        .build();

    // Send the email
    match mailer.send(&email) {
        Ok(_) => println!("Email sent successfully!"),
        Err(e) => println!("Could not send email: {:?}", e),
    }
}