diff --git a/src/ClientManager.Application/AuthApplication.cs b/src/ClientManager.Application/AuthApplication.cs
index fe569e8..72b6983 100644
--- a/src/ClientManager.Application/AuthApplication.cs
+++ b/src/ClientManager.Application/AuthApplication.cs
@@ -1,4 +1,5 @@
 using ClientManager.Application.Mappers;
+using ClientManager.Domain.Core.Interfaces.Services;
 using ClientManager.Domain.Core.Responses;
 using FluentValidation;
 
@@ -52,6 +53,18 @@ public AuthApplication(
 
             await _userService.AddUserAsync(user).ConfigureAwait(false);
 
+            _ = Task.Run(async () =>
+            {
+                try
+                {
+                    await _emailService.SendWelcomeEmailAsync(user.Email, user.Username).ConfigureAwait(false);
+                }
+                catch
+                {
+                    // fire-and-forget: email failure should not block registration
+                }
+            });
+
             var token = _tokenService.GenerateToken(user.Id, user.Username, user.Email, user.Role);
             var refreshToken = _tokenService.GenerateRefreshToken();
             _refreshTokens[refreshToken] = user.Id;
diff --git a/src/ClientManager.Infrastructure/Services/SmtpEmailService.cs b/src/ClientManager.Infrastructure/Services/SmtpEmailService.cs
index 1abcf50..3b839d4 100644
--- a/src/ClientManager.Infrastructure/Services/SmtpEmailService.cs
+++ b/src/ClientManager.Infrastructure/Services/SmtpEmailService.cs
@@ -61,7 +61,7 @@ public async Task SendWelcomeEmailAsync(string email, string name, byte[]? attac
     public async Task SendWelcomeEmailToUserAsync(string email, string username)
     {
         var host = configuration["Smtp:Host"];
-        var port = int.Parse(configuration["Smtp:Port"] ?? "587");
+        var port = int.Parse(configuration["Smtp:Port"] ?? "587", CultureInfo.InvariantCulture);
         var username2 = configuration["Smtp:Username"];
         var password = configuration["Smtp:Password"];
         var fromEmail = configuration["Smtp:FromEmail"] ?? "no-reply@clientmanager.com";