C# 发送email邮件！

利用C#邮件发送邮箱使用到两个类SmtpClient和MailMessage。可以把SmtpClient看做发送邮件信息的客户端，而把MailMessage看做需要发送的消息。

下面是我写的发送邮件的公共方法：

  /// <summary>
         ///
         /// </summary>
         /// <param name="ServerIP">发送邮件服务器ip或者域名</param>
         /// <param name="ServerPort">服务器端口</param>
         /// <param name="UserName">发件人的账号</param>
         /// <param name="Password">发件人的密码</param>
         /// <param name="FromAddress">发件人的邮箱地址</param>
         /// <param name="FromAddressName">发件人名称</param>
         /// <param name="Subject">主题</param>
         /// <param name="Body">正文</param>
         /// <param name="ToAddressList">收件人集合</param>
         /// <param name="CCAddressList">副本收件人集合</param>
         /// <param name="BccAddressList">密件抄送收件人集合</param>
         /// <param name="IsHtml">正文是否可以使用html标签</param>
         /// <param name="AttachMentFileList">附件</param>
         /// <param name="MailPriority">发送邮件的优先级 三个选项：低 中 高</param>
         /// <returns></returns>
         public String SendMail(string ServerIP, int? ServerPort, string UserName, string Password, string FromAddress, string FromAddressName, string Subject, string Body, List<string> ToAddressList, List<string> CCAddressList, List<string> BccAddressList, bool IsHtml, List<AttachmentFile> AttachMentFileList, MailPriority MailPriority)
         {
             try
             {
                 if (string.IsNullOrEmpty(ServerIP))
                 {
                     return "ServerIP 不能为空!";
                 }

                 SmtpClient mSmtpClient = new SmtpClient(ServerIP); //申明SmtpClient对象
                 System.Net.Mail.MailMessage mMailMessage = new System.Net.Mail.MailMessage(); //申明MailMessage对象

                 if (ServerPort != null)
                 {
                     mSmtpClient.Port = (int)ServerPort;
                 }

                 if (String.IsNullOrEmpty(FromAddress))
                 {
                     return "发件人不能为空";
                 }

                 if (string.IsNullOrEmpty(FromAddressName))
                 {
                     mMailMessage.From = new MailAddress(FromAddress);
                 }
                 else
                 {
                     mMailMessage.From = new MailAddress(FromAddress, FromAddressName);
                 }

                 if (string.IsNullOrEmpty(Subject))
                 {
                     return "主旨不能为空!";
                 }

                 if (ToAddressList == null || ToAddressList.Count() == )
                 {
                     return "收件人不能为空!";
                 }

                 // mSmtpClient.UseDefaultCredentials = false;
                 mSmtpClient.Credentials = new NetworkCredential(UserName, Password); //设置发送人的邮箱账号和密码，163邮箱有设置授权码
                 mSmtpClient.EnableSsl = true;  //启用ssl,也就是安全发送

                 foreach (var item in ToAddressList)  //收件者
                 {
                     mMailMessage.To.Add(item);
                 }
                 if (CCAddressList != null && CCAddressList.Count() != )
                 {
                     foreach (var item in CCAddressList)  //副本
                     {
                         mMailMessage.CC.Add(item);
                     }
                 }

                 if (BccAddressList != null && BccAddressList.Count() != )
                 {
                     foreach (var item in BccAddressList)  //密件抄送人员
                     {
                         mMailMessage.Bcc.Add(item);
                     }
                 }

                 mMailMessage.Subject = Subject;
                 mMailMessage.IsBodyHtml = IsHtml; //正文是否使用html标签展示
                 mMailMessage.Body = Body; //正文
                 mMailMessage.BodyEncoding = System.Text.Encoding.UTF8; //正文的编码原则
                 mMailMessage.Priority = MailPriority; //优先级

                 if (AttachMentFileList != null && AttachMentFileList.Count() != )  //判断是否有附件
                 {
                     foreach (var item in AttachMentFileList)
                     {
                         Attachment mAttachment = new Attachment(item.FilePath); //添加文件的文职
                         mAttachment.Name = item.FileName;//附件显示的文件名称
                         mAttachment.NameEncoding = System.Text.Encoding.UTF8;
                         mAttachment.TransferEncoding = System.Net.Mime.TransferEncoding.Base64;
                         mAttachment.ContentDisposition.Inline = true;
                         mAttachment.ContentDisposition.DispositionType = System.Net.Mime.DispositionTypeNames.Attachment;
                         mMailMessage.Attachments.Add(mAttachment);
                     }
                 }

                 mSmtpClient.Send(mMailMessage);
                 return "发送成功!";

             }
             catch (Exception ex)
             {
                 return ex.Message;
             }
         }

         public string SendMail(String ServerIP, string UserName, string Password, string FromAddress, string FromAddressName, string Subject, string Body, List<string> ToAddressList)
         {
             return SendMail(ServerIP, null, UserName, Password, FromAddress, FromAddressName, Subject, Body, ToAddressList, null, null, false, null, MailPriority.Normal);
         }
     }
     public  class AttachmentFile
     {
         /// <summary>
         /// 文件路径
         /// </summary>
         public string FilePath { get; set; }
         /// <summary>
         ///附件显示的文件明
         /// </summary>
         public string FileName { get; set; }
     }

上面的代码可以直接使用。基本的方法都有，在这儿需要说明下AttachmentFile类是我用于发送文件的时候可以重新命名文件名。

注意：大家在使用的时候注意一下参数UserName和Password，在这儿我以我163的邮箱为例，解释下这两个参数的作用。

在使用163邮箱服务器发送信息时需要按照图片上的操作开启客户端授权密码，上面的UserName和Password就是我们的邮箱地址和授权码。至于QQ邮箱我有试验过，但是就是无法发送邮件，至于你们说的开启POP3和SMTP的选项，我也已经开启了，如果知道一些原因的话，可以在下面留言告诉我！感激！

希望能帮到大家！