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

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

@@ -0,0 +1,86 @@
+//! SMTP server configuration.
+
+use serde::{Deserialize, Serialize};
+
+/// Configuration for an SMTP server instance.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SmtpServerConfig {
+    /// Server hostname for greeting and EHLO responses.
+    pub hostname: String,
+    /// Ports to listen on (e.g. [25, 587]).
+    pub ports: Vec<u16>,
+    /// Port for implicit TLS (e.g. 465). None = no implicit TLS port.
+    pub secure_port: Option<u16>,
+    /// TLS certificate chain in PEM format.
+    pub tls_cert_pem: Option<String>,
+    /// TLS private key in PEM format.
+    pub tls_key_pem: Option<String>,
+    /// Maximum message size in bytes.
+    pub max_message_size: u64,
+    /// Maximum number of concurrent connections.
+    pub max_connections: u32,
+    /// Maximum recipients per message.
+    pub max_recipients: u32,
+    /// Connection timeout in seconds.
+    pub connection_timeout_secs: u64,
+    /// Data phase timeout in seconds.
+    pub data_timeout_secs: u64,
+    /// Whether authentication is available.
+    pub auth_enabled: bool,
+    /// Maximum authentication failures before disconnect.
+    pub max_auth_failures: u32,
+    /// Socket timeout in seconds (idle timeout for the entire connection).
+    pub socket_timeout_secs: u64,
+    /// Timeout in seconds waiting for TS to respond to email processing.
+    pub processing_timeout_secs: u64,
+}
+
+impl Default for SmtpServerConfig {
+    fn default() -> Self {
+        Self {
+            hostname: "mail.example.com".to_string(),
+            ports: vec![25],
+            secure_port: None,
+            tls_cert_pem: None,
+            tls_key_pem: None,
+            max_message_size: 10 * 1024 * 1024, // 10 MB
+            max_connections: 100,
+            max_recipients: 100,
+            connection_timeout_secs: 30,
+            data_timeout_secs: 60,
+            auth_enabled: false,
+            max_auth_failures: 3,
+            socket_timeout_secs: 300,
+            processing_timeout_secs: 30,
+        }
+    }
+}
+
+impl SmtpServerConfig {
+    /// Check if TLS is configured.
+    pub fn has_tls(&self) -> bool {
+        self.tls_cert_pem.is_some() && self.tls_key_pem.is_some()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_defaults() {
+        let cfg = SmtpServerConfig::default();
+        assert_eq!(cfg.max_message_size, 10 * 1024 * 1024);
+        assert_eq!(cfg.max_connections, 100);
+        assert!(!cfg.has_tls());
+    }
+
+    #[test]
+    fn test_has_tls() {
+        let mut cfg = SmtpServerConfig::default();
+        cfg.tls_cert_pem = Some("cert".into());
+        assert!(!cfg.has_tls()); // need both
+        cfg.tls_key_pem = Some("key".into());
+        assert!(cfg.has_tls());
+    }
+}