C#编写的一个邮件的发送类

using System;
using System.ComponentModel;
using System.Text;
using System.Net;
using System.Net.Mail;

namespace Smtp
{
    public class SmtpMail
    {
        private string toAddress = "";
        private string mailUser = "";
        private string userPassword = "";
        private string displayName = "";
        private string mailSubject = "";
        private string sendMessage = "";
        private int mailPort = 0;
        private string mailHost = "";

        public string Message
        {
            get
            {
                return sendMessage;
            }
        }

        public SmtpMail(string to_address, string display_name,string mail_subject, string mail_user, string user_password,int mail_port,string mail_host)
        {
            toAddress = to_address;
            displayName = display_name;
            mailSubject = mail_subject;
            mailUser = mail_user;
            userPassword = user_password;
            mailPort = mail_port;
            mailHost = mail_host;
        }

        public void SendMail(string strBody)
        {
            System.Net.Mail.MailMessage msg = new System.Net.Mail.MailMessage();
            msg.To.Add(toAddress);
            msg.From = new MailAddress(mailUser, displayName, System.Text.Encoding.UTF8);
            msg.Subject = mailSubject;
            msg.SubjectEncoding = System.Text.Encoding.UTF8;
            msg.Body = strBody;
            msg.BodyEncoding = System.Text.Encoding.UTF8;
            msg.IsBodyHtml = false;
            msg.Priority = MailPriority.Normal;

            SmtpClient client = new SmtpClient();
            client.Credentials = new System.Net.NetworkCredential
                (mailUser, userPassword);
            client.Port = mailPort;          
            client.Host = mailHost;
            client.EnableSsl = false;
            client.SendCompleted += new SendCompletedEventHandler(client_SendCompleted);
            object userState = msg;
            try
            {
                client.SendAsync(msg, userState);
            }
            catch (System.Net.Mail.SmtpException ex)
            {
                sendMessage = ex.ToString();
            }
        }

        void client_SendCompleted(object sender, AsyncCompletedEventArgs e)
        {
            MailMessage mail = (MailMessage)e.UserState;
            string subject = mail.Subject;

            if (e.Cancelled)
            {
                string cancelled = string.Format("[{0}] Send canceled.", subject);
                sendMessage = cancelled;
            }
            if (e.Error != null)
            {
                string error = String.Format("[{0}] {1}", subject, e.Error.ToString());
                sendMessage = error;
            }
            else
            {
                sendMessage = "Message has been sent successfully!";
            }
        }
    }
}