There are a few different ways you can send email from Rust. Here are three options:

1. Use an email library: There are several libraries available for sending email from Rust, including lettre, rust-email, and mailparse. These libraries provide APIs for constructing and sending email messages.
2. Use the sendmail command: You can use Rust's std::process::Command to invoke the sendmail command, which is a common Unix utility for sending email. This approach is simple, but it requires that sendmail be installed on the system.
3. Use a web API: Many email services (e.g., Gmail, Outlook, etc.) provide APIs that you can use to send email. This approach requires an internet connection and an API key, but it allows you to send email from Rust without needing to install any libraries or utilities.

Here's an example of how you could use the lettre library to send an email from Rust:

send an email with rust

use lettre::{SmtpClient, Transport, EmailTransport, EmailAddress};
use lettre_email::Email;

fn main() {
    // Create the email
    let email = Email::builder()
        .to(EmailAddress::new("recipient@example.com"))
        .from(EmailAddress::new("sender@example.com"))
        .subject("Hello from Rust")
        .body("This is a message sent from Rust using the lettre library.")
        .build()
        .unwrap();

    // Create the SMTP client
    let client = SmtpClient::new_simple("localhost:25").unwrap();

    // Send the email
    let result = client.send(email.into());
    if result.is_ok() {
        println!("Email sent successfully!");
    } else {
        println!("Error sending email: {:?}", result);
    }
}

Here's one more example of how you can send an email using Rust:

use lettre::{Message, Transport};
use lettre_email::Email;

fn main() {
    // Create the email
    let email = Email::builder()
        .to("recipient@example.com")
        .from("sender@example.com")
        .subject("Hello")
        .body("Hello, world!")
        .build()
        .unwrap();

    // Create the transport
    let mut transport = Transport::new();

    // Send the email
    match transport.send(&email) {
        Ok(_) => println!("Email sent successfully!"),
        Err(e) => println!("Error sending email: {}", e),
    }
}

This example uses the lettre crate to send the email. You will need to add lettre and lettre_email to your Cargo.toml file:

[dependencies]
lettre = "0.10"
lettre_email = "0.10"

This example sends the email using the send method of the Transport struct, which sends the email using SMTP. You can also use other methods provided by Transport to send the email using different methods, such as sendmail or a custom transport.

I hope this helps! Let me know if you have any questions.