程序代码：

**在vs2005中使用Jmail发送邮件：

jmail.Message Jmail = new jmail.Message();

DateTime t = DateTime.Now;
String Subject = " From EMail .net";
String body = "你好科学12:15";
String FromEmail = "jsyxo@";
String ToEmail = "jjsyxo@";
//Silent属性：如果设置为true,JMail不会抛出例外错误. JMail. Send( () 会根据操作结果返回true或false
Jmail.Silent = true;
//Jmail创建的日志，前提loging属性设置为true
Jmail.Logging = true;
//字符集，缺省为"US-ASCII"
Jmail.Charset = "GB2312";
//信件的contentype. 缺省是"text/plain"） : 字符串如果你以HTML格式发送邮件, 改为"text/html"即可。
Jmail.ContentType = "text/html";
//添加收件人
Jmail.AddRecipient(ToEmail, "", "");
Jmail.From = FromEmail;
//发件人邮件用户名
Jmail.MailServerUserName = "jsyxo";
//发件人邮件密码
Jmail.MailServerPassWord = "111111";
//设置邮件标题
Jmail.Subject = Subject;
//邮件添加附件,(多附件的话，可以再加一条Jmail.AddAttachment( "c:\\test.jpg",true,null);)就可以搞定了。［注］：加了附件，讲把上面的Jmail.ContentType="text/html";删掉。否则会在邮件里出现乱码。
//Jmail.AddAttachment("c:\\test.jpg", true, null);
//邮件内容
Jmail.Body = body + t.ToString();
//Jmail发送的方法
Jmail.Send("smtp.", false);
Jmail.Close();


项目-->右键-->添加引用-->COM-->JMail 4.0 Library


自带的就有发邮件的功能的，
using System.Web.Mail;
using 群发：
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.Mail;
using System.Web.Util;
using myJmail;

using Tool;
using Manager;
using Entity;

public partial class UserControls_Jmaill : System.Web.UI.UserControl
{
string strCurrentPath = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString();
protected void Page_Load(object sender, EventArgs e)
{
}
protected void btnSend_Click(object sender, EventArgs e)
{
try
{
this.lblTitle.Text = "发送邮件控件";

myJmail.Message Jmail = new myJmail.Message();
DateTime t = DateTime.Now;
String Subject = this.txtTitle.Text;
String body = this.txtContent.Text;
string FromEmail = this.txtFormEmail.Text.Trim();//你的email
String ToEmail = this.txtToEmail.Text;//对方的email
String AddAttachment = this.FileUploadSubject.PostedFile.FileName;
//Silent属性：如果设置为true,JMail不会抛出例外错误. JMail. Send( () 会根据操作结果返回true或false
Jmail.Silent = true;
//Jmail创建的日志，前提loging属性设置为true
Jmail.Logging = true;
//字符集，缺省为"US-ASCII"
Jmail.Charset = "GB2312";
//信件的contentype. 缺省是"text/plain"） : 字符串如果你以HTML格式发送邮件, 改为"text/html"即可。
// Jmail.ContentType = "text/html";
ToEmail = ToEmail.Replace("\n", "").Replace(" ", "");
string[] str = ToEmail.Split(',');

for (int i = 0; i < str.Length; i++)
{
//添加收件人
Jmail.AddRecipient(str[i], "", "");

Jmail.From = FromEmail;
//发件人邮件用户名
Jmail.MailServerUserName = FromEmail;
//发件人邮件密码
Jmail.MailServerPassWord = "";//FromEmail邮箱的登陆密码
//设置邮件标题
Jmail.Subject = Subject;
//邮件添加附件,(多附件的话，可以再加一条Jmail.AddAttachment( "c:\\test.jpg",true,null);)就可以搞定了。［注］：加了附件，讲把上面的Jmail.ContentType="text/html";删掉。否则会在邮件里出现乱码。
Jmail.AddAttachment(AddAttachment, true, null);
//邮件内容
Jmail.Body = body + t.ToString();
//加密文件
//Jmail.PGPEncrypt = true;
//Jmail发送的方法
Jmail.Send("smtp.", false);
Jmail.ClearAttachments();
Jmail.ClearRecipients();
}
Jmail.Close();
}
catch (Exception ex)
{
this.lblMessage.Text = ex.Message;
}
}
}