sendemail.rs

// cargo add lettre
use lettre::address::Address;
use lettre::message::header::ContentType;
use lettre::message::Mailbox;
use lettre::transport::smtp::authentication::Credentials;
use lettre::{Message, SmtpTransport, Transport};

struct EmailInfo {
    credential_username: String,
    credential_password: String,
    sender_addr: String,
    sender_name: String,
    reply_addr: String,
    destination_addr: String,
    subject: String,
    content: String,
    is_html: bool,
}

fn send_email(email_info: &EmailInfo) -> Result<(), Box<dyn std::error::Error>> {
    // Define the email

    let source_address = email_info.sender_addr.parse::<Address>()?;
    let name: Option<String> = Some(email_info.sender_name.to_owned());
    let send_mailbox = Mailbox::new(name, source_address);
    let reply_addr = email_info.reply_addr.parse::<Address>()?;
    let destination_addr = email_info.destination_addr.parse::<Address>()?;
    let content_type = match email_info.is_html {
        true => ContentType::TEXT_HTML,
        false => ContentType::TEXT_PLAIN,
    };

    let email = Message::builder()
        .from(send_mailbox)
        .reply_to(reply_addr.into())
        .to(destination_addr.into())
        .subject(email_info.subject.to_owned())
        .header(content_type)
        .body(String::from(email_info.content.to_owned()))
        .unwrap();

    // Create SMTP client credentials using username and password
    let creds = Credentials::new(
        email_info.credential_username.to_owned(),
        email_info.credential_password.to_owned(),
    );

    // Open a secure connection to the SMTP server using STARTTLS
    let mailer = SmtpTransport::starttls_relay("smtp.fastmail.com")
        .unwrap() // Unwrap the Result, panics in case of error
        .credentials(creds) // Provide the credentials to the transport
        .build(); // Construct the transport

    // Attempt to send the email via the SMTP transport
    mailer.send(&email)?;
    Ok(())
}