本次的C#编程学习，带大家了解下C#.NET发EMAIL的几种方法 MailMessage/SmtpClient/CDO.Message，希望对大家学习C#编程有所帮助。

源代码如下：

using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Net.Mail;
using System.Net;
namespace Pub.Class
{
    /// <summary>
    /// 发送Email类
    /// </summary>
    public class Email
    {
        #region 私有成员
        private static object lockHelper = new object();
        private string _From;
        private string _FromEmail;
        private string _Subject;
        private string _Body;
        private string _SmtpServer;
        private string _SmtpPort = "25";
        private string _SmtpUserName;
        private string _SmtpPassword;
        private System.Web.Mail.MailFormat _Format = System.Web.Mail.MailFormat.Html;
        private System.Text.Encoding _Encoding = System.Text.Encoding.Default;
        #endregion
        #region 属性
        /// <summary>
        /// 正文内容类型
        /// </summary>
        public System.Web.Mail.MailFormat Format { set { _Format = value; } }
        /// <summary>
        /// 正文内容编码
        /// </summary>
        public System.Text.Encoding Encoding { set { _Encoding = value; } }
        /// <summary>
        /// FromEmail 发送方地址(如test@163.com) 
        /// </summary>
        public string FromEmail { set { _FromEmail = value; } }
        /// <summary>
        /// From
        /// </summary>
        public string From { set { _From = value; } }
        /// <summary>
        /// 主题
        /// </summary>
        public string Subject { set { _Subject = value; } }
        /// <summary>
        /// 内容
        /// </summary>
        public string Body { set { _Body = value; } }
        /// <summary>
        /// SmtpServer
        /// </summary>
        public string SmtpServer { set { _SmtpServer = value; } }
        /// <summary>
        /// SmtpPort
        /// </summary>
        public string SmtpPort { set { _SmtpPort = value; } }
        /// <summary>
        /// SmtpUserName
        /// </summary>
        public string SmtpUserName { set { _SmtpUserName = value; } }
        /// <summary>
        /// SmtpPassword
        /// </summary>
        public string SmtpPassword { set { _SmtpPassword = value; } }
        #endregion
        #region 构造器
        /// <summary>
        /// 构造器
        /// </summary>
        public Email() { }
        #endregion
        #region Send
        /// <summary>
        /// 发送EMAIL
        /// </summary>
        /// <example>
        /// <code>
        ///     Email _Email = new Email();
        ///     _Email.FromEmail = "test@163.com";
        ///     _Email.Subject = "<div>aaaa</div>";
        ///     _Email.Body = "aaaaaaaaaaaaa";
        ///     _Email.SmtpServer = "smtp.163.com";
        ///     _Email.SmtpUserName = "aaa";
        ///     _Email.SmtpPassword = "aaa";
        ///     _Email.Send("test@163.com");
        /// </code>
        /// </example>
        /// <param name="toEmail">收信人 接收方地址</param>
        /// <returns>成功否</returns>
        public bool SmtpMailSend(string toEmail) {
            lock (lockHelper) {
                System.Web.Mail.MailMessage msg = new System.Web.Mail.MailMessage();
                try {
                    msg.From = _FromEmail;//发送方地址(如test@163.com) 
                    msg.To = toEmail;//接收方地址
                    msg.BodyFormat = _Format;//正文内容类型
                    msg.BodyEncoding = _Encoding;//正文内容编码
                    msg.Subject = _Subject;//主题
                    msg.Body = _Body;//内容
                    msg.Fields.Add("//schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1");//设置为需要用户验证
                    if (!_SmtpPort.Equals("25")) msg.Fields.Add("//schemas.microsoft.com/cdo/configuration/smtpserverport", _SmtpPort);//设置端口
                    msg.Fields.Add("//schemas.microsoft.com/cdo/configuration/sendusername", _SmtpUserName);//设置验证用户名
                    msg.Fields.Add("//schemas.microsoft.com/cdo/configuration/sendpassword", _SmtpPassword);//设置验证密码
                    System.Web.Mail.SmtpMail.SmtpServer = _SmtpServer;//邮件服务器地址(如smtp.163.com) 
                    System.Web.Mail.SmtpMail.Send(msg);//发送 
                    return true;
                } catch { } finally {
                    
                }
            }
            return false; 
        }
        /// <summary>
        /// 发送EMAIL
        /// </summary>
        /// <param name="toEmail">Email</param>
        /// <returns>是否成功</returns>
        public bool CDOMessageSend(string toEmail) {
            lock (lockHelper) {
                CDO.Message objMail = new CDO.Message();
                try {
                    objMail.To = toEmail;
                    objMail.From = _FromEmail;
                    objMail.Subject = _Subject;
                    if (_Format.Equals(System.Web.Mail.MailFormat.Html)) objMail.HTMLBody = _Body; else objMail.TextBody = _Body;
                    //if (!_SmtpPort.Equals("25")) objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpserverport"].Value = _SmtpPort; //设置端口
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpserver"].Value = _SmtpServer;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/sendusing"].Value = 1;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpconnectiontimeout"].Value = 10;
                    objMail.Configuration.Fields.Update();
                    objMail.Send();
                    return true;
                } catch {} finally{
                    
                }
                System.Runtime.InteropServices.Marshal.ReleaseComObject(objMail);
                objMail = null;
            }
            return false; 
        }
        /// <summary>
        /// CDOMessageSend
        /// </summary>
        /// <param name="toEmail"></param>
        /// <param name="sendusing"></param>
        /// <returns></returns>
        public bool CDOMessageSend(string toEmail,int sendusing) {
            lock (lockHelper) {
                CDO.Message objMail = new CDO.Message();
                try {
                    objMail.To = toEmail;
                    objMail.From = _FromEmail;
                    objMail.Subject = _Subject;
                    if (_Format.Equals(System.Web.Mail.MailFormat.Html)) objMail.HTMLBody = _Body; else objMail.TextBody = _Body;
                    if (!_SmtpPort.Equals("25")) objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpserverport"].Value = _SmtpPort; //设置端口
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpserver"].Value = _SmtpServer;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/sendusing"].Value = sendusing;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/sendemailaddress"].Value = _FromEmail;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpuserreplyemailaddress"].Value = _FromEmail;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpaccountname"].Value = _SmtpUserName;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/sendusername"].Value = _SmtpUserName;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/sendpassword"].Value = _SmtpPassword;
                    objMail.Configuration.Fields["//schemas.microsoft.com/cdo/configuration/smtpauthenticate"].Value=1;    
                    objMail.Configuration.Fields.Update();
                    objMail.Send();
                    return true;
                } catch { } finally{
                    
                }
                System.Runtime.InteropServices.Marshal.ReleaseComObject(objMail);
                objMail = null;
            }
            return false;
        }
        /// <summary>
        /// SmtpClientSend
        /// </summary>
        /// <param name="toEmail"></param>
        /// <returns></returns>
        public bool SmtpClientSend(string toEmail) {
            lock (lockHelper) {
                System.Net.Mail.MailMessage message = new MailMessage(_FromEmail, toEmail, _Subject, _Body);
                message.SubjectEncoding = _Encoding;
                message.BodyEncoding = _Encoding;
                message.IsBodyHtml = true;
                message.Priority = MailPriority.High;
                SmtpClient client = new SmtpClient(_SmtpServer);
                client.UseDefaultCredentials = false;
                client.Credentials = new NetworkCredential(_SmtpUserName, _SmtpPassword);
                client.DeliveryMethod = SmtpDeliveryMethod.Network;
                client.Port = Str.ToInt(_SmtpPort, 587);
                client.EnableSsl = true;
                try {
                    client.Send(message);
                } catch {
                    return false;
                }
                return true;
            }
        }
        #endregion
    }
}

多线程服务调用：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration.Install;
using System.ServiceProcess;
using System.Collections;
using System.Threading;
using System.Xml;
using System.IO;
using System.Net.Mail;
using System.Runtime.Remoting.Channels.Tcp;
using System.Runtime.Remoting.Channels;
using System.Runtime.Remoting;
using Pub.Class;
using System.Diagnostics;
namespace MailService {
    [RunInstaller(true)]
    public partial class MService : ServiceBase {
        public static bool isRun = false;
        public Queue emailQueue = new Queue();
        private Thread readEmailThread;
        private Thread[] sendEmailThread;
        private string[] strList = new string[] { "MailService 启动成功！", "MailService 停止！", "{2} {1} - [{0}] - 发送失败!", "{2} {1} - [{0}] - 发送成功!", "LiveRemotingService 已启动，服务端口6669。", "LiveRemotingService 停止！" };
        private struct Config {                                                                                                                                                                                                                                     
            public string Conn;
            public string LogFile;
            public string SmtpServer;
            public string UserName;
            public string Password;
            public string FromAddress;
            public int AmountThread;
            public int RecordCount;
            public int TimeInterval;
        }
        private Config config = new Config();
        public MService() {
            System.Windows.Forms.Control.CheckForIllegalCrossThreadCalls = false;
            InitializeComponent();
            if (!System.Diagnostics.EventLog.SourceExists("MailSource")) System.Diagnostics.EventLog.CreateEventSource("MailSource", "MailServiceLog");
            this.eventLog1.Source = "MailSource";
            this.eventLog1.Log = "MailServiceLog";
            this.eventLog2.Source = "LiveRemotingSource";
            this.eventLog2.Log = "MailServiceLog";
        }
        protected override void OnStart(string[] args) {
            try {
                InitConfig();
                this.eventLog1.WriteEntry(strList[0], System.Diagnostics.EventLogEntryType.SuccessAudit);
                this.timer1.Interval = config.TimeInterval * 1000;
                this.timer1.Enabled = true;
                sendEmailThread = new Thread[config.AmountThread];
            } catch (Exception e) {
                this.eventLog1.WriteEntry(e.ToString(), System.Diagnostics.EventLogEntryType.Error);
            }
        }
        protected override void OnStop() {
            this.eventLog1.WriteEntry(strList[1], System.Diagnostics.EventLogEntryType.SuccessAudit);
            GC.Collect();
            this.timer1.Enabled = false;
        }
        private void timer1_Elapsed(object sender, System.Timers.ElapsedEventArgs e) {
            if (isRun) return;
            timer1.Enabled = false;
            readEmailThread = new Thread(new ThreadStart(ReadEmailQuque)); 
            readEmailThread.IsBackground = true;
            readEmailThread.Start();
        }
        private void InitConfig(){
            config.Conn = Pub.Class.WebConfig.GetApp("ConnString");
            config.LogFile = Pub.Class.WebConfig.GetApp("logFile");
            config.SmtpServer = Pub.Class.WebConfig.GetApp("SmtpServer");
            config.UserName = Pub.Class.WebConfig.GetApp("UserName");
            config.Password = Pub.Class.WebConfig.GetApp("Password");
            config.FromAddress = Pub.Class.WebConfig.GetApp("FromAddress");
            string amountThread = Pub.Class.WebConfig.GetApp("AmountThread");
            config.AmountThread = amountThread.Equals("") ? 1 : Convert.ToInt32(amountThread);
            config.AmountThread = config.AmountThread < 1 ? 1 : config.AmountThread;
            string recordCount = Pub.Class.WebConfig.GetApp("RecordCount");
            config.RecordCount = recordCount.Equals("") ? 1000 : Convert.ToInt32(recordCount);
            config.RecordCount = config.RecordCount < 1000 ? 1000 : config.RecordCount;
            string timeInterval = Pub.Class.WebConfig.GetApp("TimeInterval");
            config.TimeInterval = timeInterval.Equals("") ? 1000 : Convert.ToInt32(timeInterval);
            config.TimeInterval = config.TimeInterval < 2 ? 2 : config.TimeInterval;
        }
        private void ReadEmailQuque(){
            timer1.Enabled = true;
            IList<EC_EmailList> list = EC_EmailListFactory.Instance().SelectListByTop(config.RecordCount);
            if (list.Count == 0) return;
            isRun = true;
            for (int i = 0; i < list.Count; i++) {
                emailQueue.Enqueue(list[i]);
            }
            for (int i = 0; i < config.AmountThread; i++) {
                sendEmailThread[i] = new Thread(new ThreadStart(DoSendEmail));
                sendEmailThread[i].Name = "Thread" + (i+1).ToString();
                sendEmailThread[i].Start();
            }
            list = null;
        }
        private void DoSendEmail(){
            while (true) {
                EC_EmailList objMail;
                lock(this){
                    if (emailQueue.Count>0) {
                        objMail = (EC_EmailList)emailQueue.Dequeue();
                    } else {
                        isRun = false;
                        return;
                    }
                }
                int mailID = (int)objMail.EmailID;
                string strTo = objMail.To;
                string strSubject = objMail.Subject;
                string strBody = objMail.Body;
                string strFrom = objMail.From;
                string smtpServer = objMail.SmtpServer;
                string userName = objMail.UserName;
                string password = objMail.Password;
                bool isTrue = SendMail(strTo, strSubject, strBody, strFrom, smtpServer, userName, password, "");
                EC_EmailListFactory.Instance().DeleteByID(mailID);
            }
        }
        public bool SendMail(string strTo, string strSubject, string strBody,
                             string strFrom, string smtpServer, string userName,
                             string password, string attachments) {
            Email email = new Email();
            string strSmtpServer = smtpServer.Length > 0 ? smtpServer : config.SmtpServer.Trim();
            email.SmtpServer = strSmtpServer;
            email.SmtpUserName = userName.Length > 0 ? userName : config.UserName.Trim();
            email.SmtpPassword = password.Length > 0 ? password : config.Password.Trim();
            email.SmtpPort = strSmtpServer.ToLower().Contains("gmail") ? "587" : "25";
            email.EnableSsl = strSmtpServer.ToLower().Contains("gmail") ? true : false;
            email.FromEmail = strFrom.Length > 0 ? strFrom : config.FromAddress.Trim();
            email.Subject = strSubject;
            email.Body = strBody;
            email.Encoding = System.Text.Encoding.UTF8;
            bool isSuccess = email.SmtpClientSend(strTo);
            return isSuccess;
        }
        public void ErrorLog(string strMessage) {
            lock(this){
                StreamWriter sw = new StreamWriter(config.LogFile + "MailLog.txt", true);
                sw.WriteLine(strMessage);
                sw.Flush();
                sw.Close();
            }
        }
    }
}

曾经运行在MSN的MCLUB的服务器上跑发EMAIL的服务。应该是安全无死锁调用。

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