feat: add POP3 server

AGENTS.md

@@ -23,31 +23,15 @@ smtp4dev is a fake SMTP email server for development and testing, built as a .NE
    - Takes approximately 40-60 seconds
    - NEVER CANCEL - Set timeout to 120+ seconds
 
-2. **Install frontend dependencies:**
-   ```bash
-   cd Rnwood.Smtp4dev/ClientApp
-   npm install
-   ```
-   - Takes approximately 35-50 seconds
-   - NEVER CANCEL - Set timeout to 120+ seconds
-   - May show peer dependency warnings (expected and harmless)
-
-3. **Build the application:**
+2. **Build the application:**
    ```bash
    # Build main web application (recommended for development)
-   dotnet build Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj -c Release
+   dotnet build Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj
    ```
    - Takes approximately 3-5 seconds after initial frontend build
    - NEVER CANCEL - Set timeout to 60+ seconds
    - The Desktop project will fail on Linux (expected - Windows-only)
 
-4. **Publish the application:**
-   ```bash
-   dotnet publish Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj -c Release -o ./published
-   ```
-   - Takes approximately 20-25 seconds including frontend Vite build
-   - NEVER CANCEL - Set timeout to 120+ seconds
-
 ### Run the Application
 
 **Development mode (with live reload):**
@@ -57,6 +41,9 @@ dotnet run --project Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj --urls="http://local
 
 **Published mode:**
 ```bash
+
+dotnet publish Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj -c Release -o ./published
+
 cd ./published
 ./Rnwood.Smtp4dev --urls="http://localhost:5000" --smtpport=2525 --imapport=1143
 ```
@@ -92,12 +79,6 @@ npm run lint
 - Takes approximately 10-15 seconds
 - Some configuration warnings are expected
 
-**Frontend Tests:**
-```bash
-cd Rnwood.Smtp4dev/ClientApp
-npm test -- --passWithNoTests
-```
-- Currently has Jest configuration issues (known limitation)
 
 ### Validation Scenarios
 
@@ -168,16 +149,11 @@ npm test -- --passWithNoTests
 3. **Always run validation scenarios** after changes
 4. Test both development and published modes
 
-### Frontend Development
-```bash
-cd Rnwood.Smtp4dev/ClientApp
-npm run dev  # Development server with hot reload (runs on port 5173)
-```
-
-### Backend Development
+### Full Stack Development
 ```bash
 dotnet watch run --project Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj
 ```
+Both the front end and backend will reload on changes.
 
 ### Configuration
 - Default configuration in `appsettings.json` with extensive inline documentation
@@ -248,7 +224,6 @@ type(optional-scope): description
 - **Database locks**: Application creates SQLite database in user config directory
 
 ### Testing Issues
-- **Jest configuration errors**: Known issue with current module configuration
 - **E2E test complexity**: Requires Chrome and specific environment setup
 - **Network-dependent tests**: May fail in restricted environments
 
@@ -263,29 +238,4 @@ The project uses Azure Pipelines (`azure-pipelines.yml`) with:
 **Build matrix includes:**
 - `win-x64`, `linux-x64`, `linux-musl-x64`, `linux-arm`, `win-arm64`
 - Desktop variants (Windows only)
-- Docker images (Linux and Windows)
-
-## Command Reference
-
-### Essential Commands
-```bash
-# Quick development setup
-dotnet restore && cd Rnwood.Smtp4dev/ClientApp && npm install && cd ../..
-
-# Build for development
-dotnet build Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj -c Release
-
-# Run with development settings
-dotnet run --project Rnwood.Smtp4dev/Rnwood.Smtp4dev.csproj --urls="http://localhost:5000" --smtpport=2525
-
-# Test SMTP functionality
-echo -e "HELO test\nMAIL FROM:<test@example.com>\nRCPT TO:<user@example.com>\nDATA\nSubject: Test\n\nTest message\n.\nQUITS" | nc localhost 2525
-
-# Check web UI
-curl -s http://localhost:5000/ && echo "Web UI is running"
-
-# Check API
-curl -s http://localhost:5000/api/messages | jq '.results | length'
-```
-
-Always ensure the application is fully functional by testing email sending, web UI access, and API responses after making any changes.
+- Docker images (Linux and Windows)

Dockerfile.linux

@@ -12,4 +12,5 @@ ENV DOTNET_USE_POLLING_FILE_WATCHER true
 EXPOSE 80
 EXPOSE 25
 EXPOSE 143
+EXPOSE 110
 ENTRYPOINT ["dotnet", "/app/Rnwood.Smtp4dev.dll"]

Dockerfile.linux.arm64

@@ -12,4 +12,5 @@ ENV DOTNET_USE_POLLING_FILE_WATCHER true
 EXPOSE 80
 EXPOSE 25
 EXPOSE 143
+EXPOSE 110
 ENTRYPOINT ["dotnet", "/app/Rnwood.Smtp4dev.dll"]

Dockerfile.windows.ltsc2019

@@ -4,6 +4,7 @@ COPY out /app
 EXPOSE 80
 EXPOSE 25
 EXPOSE 143
+EXPOSE 110
 ENV ASPNETCORE_HTTP_PORTS 80
 ENV SERVEROPTIONS__URLS http://*:80
 VOLUME c:\smtp4dev

Dockerfile.windows.ltsc2022

@@ -4,6 +4,7 @@ COPY out /app
 EXPOSE 80
 EXPOSE 25
 EXPOSE 143
+EXPOSE 110
 ENV ASPNETCORE_HTTP_PORTS 80
 ENV SERVEROPTIONS__URLS http://*:80
 VOLUME c:\smtp4dev

README.md

@@ -5,7 +5,7 @@ A dummy SMTP server for Windows, Linux, Mac OS-X (and maybe elsewhere where .NET
 
 smtp4dev support many advanced features:
 - OpenAPI/Swagger API
-- IMAP access to retrieve and delete messages
+- IMAP and POP3 access to retrieve and delete messages
 - SMTP session logging
 - UTF8 support
 - Viewport size switcher to simulate mobile etc

Rnwood.Smtp4dev.Tests/E2E/E2ECollection.cs

@@ -0,0 +1,10 @@
+using Xunit;
+
+namespace Rnwood.Smtp4dev.Tests.E2E
+{
+    [CollectionDefinition("E2E", DisableParallelization = true)]
+    public class E2ECollectionDefinition
+    {
+        // Collection definition intentionally left empty - used to disable parallelization for E2E tests
+    }
+}

Rnwood.Smtp4dev.Tests/E2E/E2ETests.cs

@@ -15,7 +15,7 @@ namespace Rnwood.Smtp4dev.Tests.E2E
 {
     public class E2ETests
     {
-        private readonly ITestOutputHelper output;
+        protected readonly ITestOutputHelper output;
 
         public E2ETests(ITestOutputHelper output)
         {
@@ -37,6 +37,8 @@ public class E2ETestContext
             public int SmtpPortNumber { get; set; }
 
             public int ImapPortNumber { get; set; }
+            public int Pop3PortNumber { get; set; }
+            public string Pop3Host { get; set; } = "localhost";
         }
 
 
@@ -117,6 +119,11 @@ protected void RunE2ETest(Action<E2ETestContext> test, E2ETestOptions options =
                 args.Add("--imapport=0");
             }
 
+            if (!args.Any(a => a.StartsWith("--pop3port")))
+            {
+                args.Add("--pop3port=0");
+            }
+
             if (!args.Any(a => a.StartsWith("--smtpport")))
             {
                 args.Add("--smtpport=0");
@@ -134,9 +141,9 @@ protected void RunE2ETest(Action<E2ETestContext> test, E2ETestOptions options =
 
 
 
-            if (!string.IsNullOrEmpty(options.BasePath))
+            if (string.IsNullOrEmpty(options.BasePath))
             {
-                args.Add($"--basepath={options.BasePath}");
+                args.Add("--basepath=");
             }
 
             output.WriteLine("Args: " + string.Join(" ", args.Select(a => $"\"{a}\"")));
@@ -154,9 +161,11 @@ protected void RunE2ETest(Action<E2ETestContext> test, E2ETestOptions options =
                     Uri baseUrl = null;
                     int? smtpPortNumber = null;
                     int? imapPortNumber = null;
+                    int? pop3PortNumber = null;
+                    string pop3Host = "localhost";
 
 
-                    while ((baseUrl == null || !smtpPortNumber.HasValue || !imapPortNumber.HasValue) && serverOutput.MoveNext())
+                    while ((baseUrl == null || !smtpPortNumber.HasValue || !imapPortNumber.HasValue || !pop3PortNumber.HasValue) && serverOutput.MoveNext())
                     {
                         string newLine = serverOutput.Current;
                         output.WriteLine(newLine);
@@ -183,6 +192,31 @@ protected void RunE2ETest(Action<E2ETestContext> test, E2ETestOptions options =
                             imapPortNumber = (binary == "docker" && internalImapPort == 143) ? 1143 : internalImapPort;
                         }
 
+                        if (newLine.StartsWith("POP3 Server is listening on port"))
+                        {
+                            int internalPop3Port = int.Parse(Regex.Replace(newLine, @"POP3 Server is listening on port (\d+).*", "$1"));
+                            // For Docker, map internal port 110 to external port 1100
+                            pop3PortNumber = (binary == "docker" && internalPop3Port == 110) ? 1100 : internalPop3Port;
+                            // Try to parse the address from the same line (e.g. "POP3 Server is listening on port 53333 (::)")
+                            var m = Regex.Match(newLine, @"POP3 Server is listening on port \d+ \(([^)]+)\)");
+                            if (m.Success)
+                            {
+                                var addr = m.Groups[1].Value;
+                                if (addr == "::" || addr == "::1" || addr.Contains(':'))
+                                {
+                                    pop3Host = "::1";
+                                }
+                                else if (addr == "0.0.0.0")
+                                {
+                                    pop3Host = "127.0.0.1";
+                                }
+                                else
+                                {
+                                    pop3Host = addr;
+                                }
+                            }
+                        }
+
                         if (newLine.StartsWith("Application started. Press Ctrl+C to shut down."))
                         {
                             throw new Exception($@"Startup completed but did not catch variables from startup output:
@@ -207,11 +241,14 @@ protected void RunE2ETest(Action<E2ETestContext> test, E2ETestOptions options =
                     Assert.False(serverProcess.Process.HasExited, "Server process failed");
 
 
+                    output.WriteLine($"Using Pop3Host: {pop3Host}, Pop3Port: {pop3PortNumber}");
                     test(new E2ETestContext
                     {
                         BaseUrl = baseUrl,
                         SmtpPortNumber = smtpPortNumber.Value,
-                        ImapPortNumber = imapPortNumber.Value
+                        ImapPortNumber = imapPortNumber.Value,
+                        Pop3PortNumber = pop3PortNumber.Value,
+                        Pop3Host = pop3Host
                     });
                 }
                 finally