اتصال به ایمیل‌سرور در برنامه‌های NET.

MAIL_HOST=smtp.c1.liara.email
MAIL_PORT=587
MAIL_USERNAME=my-app
MAIL_PASSWORD=my-pass

using System;
using System.Net;
using System.Net.Mail;
using System.IO;
using dotenv.net;

class Program
{
    static void Main()
    {
        DotEnv.Load(); // loading env variables 

        string mailHost = Environment.GetEnvironmentVariable("MAIL_HOST");
        int mailPort = int.Parse(Environment.GetEnvironmentVariable("MAIL_PORT"));
        string mailUser = Environment.GetEnvironmentVariable("MAIL_USERNAME");
        string mailPassword = Environment.GetEnvironmentVariable("MAIL_PASSWORD");

        // SMTP Conf
        SmtpClient client = new SmtpClient(mailHost)
        {
            Port = mailPort,
            Credentials = new NetworkCredential(mailUser, mailPassword),
            EnableSsl = true
        };

        // Creating and Sending Email  
        MailMessage message = new MailMessage("from@test.com", "to@test.com",
         "hello", "hello from dotnet!");
        try
        {
            client.Send(message);
            Console.WriteLine("email sent successfully");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"error in sending email: {ex.Message}");
        }
    }
}

using MimeKit;
using MailKit.Net.Smtp;
using DotNetEnv; // for install this, run: dotnet install add package DotNetEnv

namespace your_project_name.Controllers; 

public class TestController : Controller
{
    [HttpPost]
    public IActionResult SendEmail(string email)
    {   
        // Email Information  
        Env.Load();
        string senderName  = Env.GetString("SENDER_NAME");
        string senderEmail = Env.GetString("SENDER_ADDRESS");
        string subject     = Env.GetString("EMAIL_SUBJECT");
        string body        = Env.GetString("EMAIL_BODY");

        // Email Instance
        var message = new MimeMessage();
        message.From.Add(new MailboxAddress(senderName, senderEmail));
        message.To.Add(new MailboxAddress("Recipient", email));
        message.Subject = subject;

        // Creating The Body 
        message.Body = new TextPart("plain")
        {
            Text = body
        };

        try
        {
            // Sending Email 
            using (var client = new SmtpClient())
            {
                client.Connect(Env.GetString("MAIL_HOST"), Env.GetInt("MAIL_PORT"), false);
                client.Authenticate(Env.GetString("MAIL_USERNAME"), Env.GetString("MAIL_PASSWORD"));
                client.Send(message);
                client.Disconnect(true);
            }

            ViewBag.Message = "Email Sent Successfully.";
        }
        catch (Exception ex)
        {
            ViewBag.Message = $"Error In Sending Email: {ex.Message}";
        }


        return RedirectToAction("Index");
    }

}