Getting Started Guide

Install Zetian SMTP Server and run your first server in minutes.

Requirements

• Windows, Linux, or macOS
• .NET 6.0, 7.0, 8.0, 9.0, or 10.0
• Administrator/root privileges (for low port numbers)

Installation

Add Zetian to your project using NuGet Package Manager:

dotnet add package Zetian

Alternatively, you can use Package Manager Console in Visual Studio or .NET CLI.Visit NuGet page →

Your First SMTP Server

Create a simple SMTP server:

Program.cs

using Zetian;

// Create a simple SMTP server
using var server = SmtpServerBuilder.CreateBasic();

// When message is received
server.MessageReceived += (sender, e) =>
{
    Console.WriteLine($"From: {e.Message.From}");
    Console.WriteLine($"To: {string.Join(", ", e.Message.Recipients)}");
    Console.WriteLine($"Subject: {e.Message.Subject}");
};

// Start the server
await server.StartAsync();
Console.WriteLine($"SMTP Server running on {server.Endpoint}");

// Keep the server running
Console.ReadLine();

Port 25

Default SMTP port

Event-Driven

Listen to message events

Async/Await

Modern async pattern

Add Authentication

Add authentication mechanism for security:

Program.cs

using Zetian;

// Authenticated server
using var server = new SmtpServerBuilder()
    .Port(587)
    .RequireAuthentication()
    .AllowPlainTextAuthentication() // For testing without TLS
    .SimpleAuthentication("admin", "password123")
    .Build();

// When a message is received from an authenticated user
server.MessageReceived += (sender, e) =>
{
    if (e.Session.IsAuthenticated)
    {
        Console.WriteLine($"Authenticated user: {e.Session.AuthenticatedIdentity}");
        Console.WriteLine($"Subject: {e.Message.Subject}");
    }
};

await server.StartAsync();

TLS/SSL Security

Add encrypted connection support with STARTTLS:

Program.cs

using Zetian;

// Secure server with TLS/SSL support
using var server = new SmtpServerBuilder()
    .Port(587)
    .Certificate("certificate.pfx", "cert_password")
    .RequireSecureConnection()
    .RequireAuthentication()
    .Build();

await server.StartAsync();

🎉 Congratulations! Your first SMTP server is ready!

Now you're ready to learn more advanced features:

Configuration

Customize server settings

Message Processing

Events and message management