io-smtp

I/O-free SMTP client library.

This library provides I/O-free coroutines for managing SMTP streams. It is based on the smtp-codec crate for protocol encoding/decoding.

Features

• I/O-free coroutine-based design
• No runtime dependencies (works with any async/sync I/O)
• Full SMTP protocol support
• STARTTLS support
• AUTH PLAIN authentication

Available Coroutines

• greeting - Read server greeting (220)
• ehlo - Send EHLO and receive capabilities
• starttls - Upgrade to TLS
• authenticate_plain - AUTH PLAIN authentication
• mail - MAIL FROM command
• rcpt - RCPT TO command
• data - DATA command with message body
• noop - NOOP command
• rset - RSET command
• quit - QUIT command

Example

use io_smtp::{context::SmtpContext, coroutines::greeting::GetSmtpGreeting};

let context = SmtpContext::new();
let mut coroutine = GetSmtpGreeting::new(context);

loop {
    match coroutine.resume(io_result) {
        GetSmtpGreetingResult::Ok { context, greeting } => {
            // Connection established, server ready
            break;
        }
        GetSmtpGreetingResult::Io { io } => {
            // Perform I/O operation and feed result back
            io_result = Some(perform_io(&mut stream, io));
        }
        GetSmtpGreetingResult::Err { err, .. } => {
            panic!("Error: {err}");
        }
    }
}

License

MIT