optimize code

Author: tinohager

Src/SmtpServer/ISmtpServerOptions.cs

@@ -44,10 +44,10 @@ public interface ISmtpServerOptions
         int NetworkBufferSize { get; }
 
         /// <summary>
-        /// Gets the custom greeting message sent by the server in response to the initial SMTP connection.
-        /// This message is returned after the client connects and before any commands are issued (e.g., "220 mail.example.com v1.0 ESMTP ready").
-        /// If not set, a default greeting will be used.
+        /// Gets the custom SMTP greeting message that the server sends immediately after a client connects,
+        /// typically as the initial "220" response. The message can be dynamically generated based on the session context.
+        /// If not set, a default greeting will be used (e.g., "220 mail.example.com ESMTP ready").
         /// </summary>
-        string CustomGreetingMessage { get; }
+        Func<ISessionContext, string> CustomSmtpGreeting { get; }
     }
 }

Src/SmtpServer/SmtpServerOptionsBuilder.cs

@@ -24,7 +24,7 @@ public ISmtpServerOptions Build()
                 MaxAuthenticationAttempts = 3,
                 NetworkBufferSize = 128,
                 CommandWaitTimeout = TimeSpan.FromMinutes(5),
-                CustomGreetingMessage = null,
+                CustomSmtpGreeting = null,
             };
 
             _setters.ForEach(setter => setter(serverOptions));
@@ -162,11 +162,15 @@ public SmtpServerOptionsBuilder CommandWaitTimeout(TimeSpan value)
         /// Sets the custom SMTP greeting message sent to the client upon connection,
         /// typically returned as the initial "220" response.
         /// </summary>
-        /// <param name="value">The greeting message to send to the client (e.g., "220 mail.example.com v1.0 ESMTP ready").</param>
+        /// <param name="smtpGreetingFunc">
+        /// A delegate that returns the greeting message to send to the client,
+        /// based on the <see cref="ISessionContext"/> (e.g., client IP, TLS state).
+        /// Example: <c>ctx => $"220 {sessionContext.ServerOptions.ServerName} ESMTP ready"</c>
+        /// </param>
         /// <returns>An OptionsBuilder to continue building on.</returns>
-        public SmtpServerOptionsBuilder CustomGreetingMessage(string value)
+        public SmtpServerOptionsBuilder CustomGreetingMessage(Func<ISessionContext, string> smtpGreetingFunc)
         {
-            _setters.Add(options => options.CustomGreetingMessage = value);
+            _setters.Add(options => options.CustomSmtpGreeting = smtpGreetingFunc);
 
             return this;
         }
@@ -220,7 +224,7 @@ class SmtpServerOptions : ISmtpServerOptions
             /// This message is returned after the client connects and before any commands are issued (e.g., "220 mail.example.com v1.0 ESMTP ready").
             /// If not set, a default greeting will be used.
             /// </summary>
-            public string CustomGreetingMessage { get; set; }
+            public Func<ISessionContext, string> CustomSmtpGreeting { get; set; }
         }
 
         #endregion

Src/SmtpServer/SmtpSession.cs

@@ -189,14 +189,14 @@ static async Task<bool> ExecuteAsync(SmtpCommand command, SmtpSessionContext con
         /// <returns>A task which performs the operation.</returns>
         ValueTask<FlushResult> OutputGreetingAsync(CancellationToken cancellationToken)
         {
-            if (_context.ServerOptions.CustomGreetingMessage is null)
+            if (_context.ServerOptions.CustomSmtpGreeting is null)
             {
                 var serverVersion = AssemblyVersion;
                 _context.Pipe.Output.WriteLine($"220 {_context.ServerOptions.ServerName} v{serverVersion} ESMTP ready");
             }
             else
             {
-                _context.Pipe.Output.WriteLine($"220 {_context.ServerOptions.ServerName} {_context.ServerOptions.CustomGreetingMessage}");
+                _context.Pipe.Output.WriteLine(_context.ServerOptions.CustomSmtpGreeting(_context));
             }
 
             return _context.Pipe.Output.FlushAsync(cancellationToken);