feat(mailer-smtp): implement in-process SMTP server and management IPC integration

rust/crates/mailer-smtp/src/lib.rs

@@ -1,18 +1,39 @@
 //! mailer-smtp: SMTP protocol engine (server + client).
+//!
+//! This crate provides the SMTP protocol implementation including:
+//! - Command parsing (`command`)
+//! - State machine (`state`)
+//! - Response building (`response`)
+//! - Email data accumulation (`data`)
+//! - Per-connection session state (`session`)
+//! - Address/input validation (`validation`)
+//! - Server configuration (`config`)
+//! - Rate limiting (`rate_limiter`)
+//! - TCP/TLS server (`server`)
+//! - Connection handling (`connection`)
+
+pub mod command;
+pub mod config;
+pub mod connection;
+pub mod data;
+pub mod rate_limiter;
+pub mod response;
+pub mod server;
+pub mod session;
+pub mod state;
+pub mod validation;
 
 pub use mailer_core;
 
-/// Placeholder for the SMTP server and client implementation.
+// Re-export key types for convenience.
+pub use command::{AuthMechanism, SmtpCommand};
+pub use config::SmtpServerConfig;
+pub use data::{DataAccumulator, DataAction};
+pub use response::SmtpResponse;
+pub use session::SmtpSession;
+pub use state::SmtpState;
+
+/// Crate version.
 pub fn version() -> &'static str {
     env!("CARGO_PKG_VERSION")
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_version() {
-        assert!(!version().is_empty());
-    }
-}