｛求助｝c#邮件发面的协议语法

学c#一年了还没有做过网络发面的软件求一个收发邮件的协议 --------------------编程问答--------------------

界面做好了就差这方面的协议，下午图书馆去查资料去了

大神些给点资料 --------------------编程问答-------------------- using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;
using System.Windows.Forms;
using System.Net.Mail;
using System.IO;
using System.Net.Mime;
using System.Net;

namespace MailTo
{
    class MailHelper
    {
        public string smtp;
        public string from;
        public string displayname;
        public string pwd;
        public string to;
        public string subject;
        public string body;
        public ArrayList paths;
        public bool blnUseSSL;
        public MailHelper(string Psmtp, string Pfrom, string Ppwd, string Pdisplayname, string Pto, string Psubject, string Pbody, ArrayList Ppaths, bool PblnUseSSL)
        {
            smtp = Psmtp;
            from = Pfrom;
            displayname = Pdisplayname;
            pwd = Ppwd;
            to = Pto;
            subject = Psubject;
            body = Pbody;
            paths = Ppaths;
            blnUseSSL = PblnUseSSL;
        }

        public bool SendMail()
        {
            MailMessage mail = new MailMessage();
            mail.From = new MailAddress(from, displayname, Encoding.UTF8);
            mail.To.Add(to);
            mail.Subject = subject;
            mail.SubjectEncoding = Encoding.Default;
            mail.Body = body;
            mail.BodyEncoding = Encoding.Default;
            mail.IsBodyHtml = false;
            mail.Priority = MailPriority.Normal;
            //添加附件
            Attachment attachment = null;
            if (paths.Count > 0)
            {
                for (int i = 0; i < paths.Count; i++)
                {
                    string pathFileName = paths[i].ToString();
                    string extName = Path.GetExtension(pathFileName).ToLower();
                    //判断附件类型
                    if (extName == ".rar" || extName == ".zip")
                    {
                        attachment = new Attachment(pathFileName, MediaTypeNames.Application.Zip);
                    }
                    else
                    {
                        attachment = new Attachment(pathFileName, MediaTypeNames.Application.Octet);
                    }
                    ContentDisposition cd = attachment.ContentDisposition;
                    cd.CreationDate = File.GetCreationTime(pathFileName);
                    cd.ModificationDate = File.GetLastWriteTime(pathFileName);
                    cd.ReadDate = File.GetLastAccessTime(pathFileName);
                    mail.Attachments.Add(attachment);
                }
            }
            SmtpClient client = new SmtpClient();
            client.Host = smtp;
            client.Port = 25;
            //是否使用安全套接字层加密连接
            client.EnableSsl = blnUseSSL;
            //不使用默认凭证，注意此句必须放在 client.Credentials 的上面
            client.UseDefaultCredentials = false;
            client.Credentials = new NetworkCredential(from, pwd);
            //邮件通过网络直接发送到服务器
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            try
            {
                client.Send(mail);
                return true;
            }
            catch
            {
                return false;
            }
            finally
            {
                mail.Dispose();
                client = null;
            }
        }
    }
}
--------------------编程问答-------------------- 这是发邮件的。可以参考下 --------------------编程问答-------------------- 收发邮件是标准协议，你不能自定义的，可以用.net自带的也可以用第三方的如，jmail

补充：.NET技术 ,  C#