What is the purpose of the SMTP

In this article I’ll try to explain how we can send emails using SMTP servers.

• Protocol
  Protocol is a group of rules which is used by applications that communicate each other from network.
• SMTP — Simple Mail Transfer Protocol.
  Is a protocol used to transfer emails.First RFC was published in August 1982.We can say that when we compose a message in an outlook application and send it, the outlook application sends this email to mail server by using the smtp protocol.

c# import and export excel ,send email using smtp-pulse

ALL THE CODE

using OfficeOpenXml;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Mail;
using System.Net.Mime;
using System.Text;
using System.Threading.Tasks;
namespace ConsoleApp6
{
  public class User
  {
    public int Id { get; set; }
    public string Name { get; set; }
    public string Surname { get; set; }
  }
    class Program
    {
      static void Main(string[] args)
      {
      List<User> userList = new List<User>();
      userList.Add(new User {
        Id=1,
        Name="ilhan",
        Surname="Demirtepe"
      });
      userList.Add(new User
      {
        Id = 2,
        Name = "Akif",
        Surname = "Demirtepe"
      });
      userList.Add(new User
      {
        Id = 3,
        Name = "Mehmet",
        Surname = "Demirtepe"
      });
      using (ExcelPackage excel = new ExcelPackage())
      {
        excel.Workbook.Worksheets.Add("Worksheet1");
        var worksheet = excel.Workbook.Worksheets["Worksheet1"];
        worksheet.Cells[1, 1].Value = "Id";
        worksheet.Cells[1, 2].Value = "Name";
        worksheet.Cells[1, 3].Value = "Surname";
        int recordIndex = 2;
        foreach (var article in userList)
        {
          worksheet.Cells[recordIndex, 1].Value = article.Id;
          worksheet.Cells[recordIndex, 2].Value = article.Name;
          worksheet.Cells[recordIndex, 3].Value = article.Surname;
          recordIndex++;
        }
        // AutoFit() method here.
        worksheet.Column(1).AutoFit();
        worksheet.Column(2).AutoFit();
        worksheet.Column(3).AutoFit();
        string root = Path.Combine("Content");
        if (!Directory.Exists(root))
        {
             Directory.CreateDirectory(root);
        }
        string subdir = Path.Combine("Content/" + "Customer.xlsx");
        FileInfo excelFile = new FileInfo(subdir);
        excel.SaveAs(excelFile);
        FileStream streamTemp = System.IO.File.Open(subdir, FileMode.Open, FileAccess.Read);
        byte[] m_Bytes = ReadToEnd(streamTemp);
        Attachment attachment = WrapExcelBytesInAttachment(m_Bytes);
        SendEmail("fromemailadres", "DisplayName", "Subject","ilhandemirtepe@gmail.com", attachment);
        }
      }
      static Attachment WrapExcelBytesInAttachment(byte[] excelContent)
      {
      try
      {
        string subdir = Path.Combine("Content/" + "Customer.xlsx");
        Stream stream = new MemoryStream(excelContent);
        Attachment attachment = new Attachment(stream, subdir);
        attachment.ContentType = new ContentType("application/vnd.ms-excel");
        return attachment;
      }
      catch (Exception ex)
      {
         return null;
      }
      }
      static bool SendEmail(string fromEmailAddress, string fromDisplayName, string fromSubject, string toEmailAddress, Attachment message)
      {
        bool result = false;
        try
        {
        MailMessage ePosta = new MailMessage();
        ePosta.From = new MailAddress(fromEmailAddress, fromDisplayName);
        ePosta.To.Add(toEmailAddress);
        ePosta.Subject = fromSubject;
        ePosta.Body = "deneme";
        ePosta.IsBodyHtml = true;
        int port = 587; ///server email port
        string host = "smtp-pulse.com";
        string emailaddress = "xyz@abc.com"; ///server email adress
        string password = "123456"; ///server email password
        SmtpClient smtp = new SmtpClient();
        smtp.Credentials = new System.Net.NetworkCredential(emailaddress, password);
        smtp.Port = port;
        smtp.Host = host;
        smtp.EnableSsl = false;
        try
        {
          ePosta.IsBodyHtml = true;
          if (message != null)
          {
                ePosta.Attachments.Add(message);
          }
          smtp.Send(ePosta);
          result = true;
        }
        catch (SmtpException ex)
        {
            throw new Exception(ex.Message);
        }
        }
        catch (Exception)
        {
              return result;
        }
        return result;
        }
        public static byte[] ReadToEnd(System.IO.Stream stream)
        {
          long originalPosition = 0;
          if (stream.CanSeek)
          {
            originalPosition = stream.Position;
            stream.Position = 0;
          }
          try
          {
              byte[] readBuffer = new byte[4096];
              int totalBytesRead = 0;
              int bytesRead;
              while ((bytesRead = stream.Read(readBuffer, totalBytesRead, readBuffer.Length - totalBytesRead)) > 0)
              {
                 totalBytesRead += bytesRead;
                if (totalBytesRead == readBuffer.Length)
                {
                    int nextByte = stream.ReadByte();
                    if (nextByte != -1)
                    {
                        byte[] temp = new byte[readBuffer.Length * 2];
                        Buffer.BlockCopy(readBuffer, 0, temp, 0, readBuffer.Length);
                        Buffer.SetByte(temp, totalBytesRead, (byte)nextByte);
                        readBuffer = temp;
                        totalBytesRead++;
                    }
                }
              }
               byte[] buffer = readBuffer;
               if (readBuffer.Length != totalBytesRead)
                {
                  buffer = new byte[totalBytesRead];
                  Buffer.BlockCopy(readBuffer, 0, buffer, 0, totalBytesRead);
                }
                 return buffer;
           }
         finally
         {
            if (stream.CanSeek)
            {
                stream.Position = originalPosition;
            }
          }
        }
  }
}