C# 邮件发送系统

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Mail;
using System.Net;
using System.IO;
using System.Net.Mime;
using System.Threading;

private void Form1_Load(object sender, EventArgs e)
        {
            comboBoxEx3.SelectedIndex = 0;
            txtMailFrom.SelectedIndex = 0;
            txtSmtpServer.SelectedIndex = 0;
            txtMailTo.SelectedIndex = 0;
        }
        //发送邮件
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (IsValid())
            {
                if (MessageBox.Show("您确定要发送当前邮件吗？", "询问", MessageBoxButtons.OKCancel, MessageBoxIcon.Question) == DialogResult.OK)
                {
                    string serverHost = "smtp." + txtSmtpServer.Text + comboBoxEx3.Text; //smtp 地址
                    int port = Int32.Parse(numericUpDown1.Value.ToString());    //smtp 密码
                    string mailFrom = txtMailFromEx.Text + "@" + txtMailFrom.Text; //发信人,必须是提供smtp服务的邮件服务器 
                    string mailPwd = txtformPwd.Text;   //密码
                    string displayName = txtDisplayName.Text;   //显示名
                    string mailSubject = txtMailSubject.Text;   //主题
                    string mailBody = txtMailBody.Text;   //正文
                    string file = string.IsNullOrEmpty(txtPath.Text) ? null : txtPath.Text;
                    int contactNum = dgvContact.Rows.Count - 1; //联系人数量
                    //循环给每个联系人发送指定数量的邮件
                    for (int i = 0; i < contactNum; i++)
                    {
                        string mailTo = dgvContact.Rows[i].Cells[0].Value.ToString();  //收件人
                        //发送指定数量的邮件
                        for (int j = 1; j <= Int32.Parse(txtNum.Text); j++)
                        {
                            try
                            {
                                EmailHelper.SendEmail(serverHost, port, mailFrom, mailPwd, displayName, mailTo, mailSubject, mailBody, file);
                            }
                            catch (Exception ex)
                            {
                                MessageBox.Show(ex.Message);
                            }
                        }
                    }
                }
            }
        }
        //验证输入是否有误
        private bool IsValid()
        {
            //检测附件大小 发件必需小于10M 否则返回  不会执行以下代码
            if (txtPath.Text != "")
            {
                if (!EmailHelper.CheckAttachment(txtPath.Text.Trim()))
                {
                    return false;
                }
            }
            if (txtSmtpServer.Text == "")
            {
                MessageBox.Show("请输入SMTP服务器名！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            if (txtMailFromEx.Text == "")
            {
                MessageBox.Show("请输入发件人邮箱地址！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            if (txtformPwd.Text == "")
            {
                MessageBox.Show("请输入发件人邮箱密码！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }

            if (dgvContact.Rows.Count <= 1)
            {
                MessageBox.Show("请添加收件人！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return false;
            }
            return true;
        }
        //添加联系人
        int i = 1;  //拼接联系人描述字段，加入联系人框
        private void btnAddContact_Click(object sender, EventArgs e)
        {
            string Contact = txtMailToEx.Text + "@" + txtMailTo.Text;
            for (int m = 0; m < dgvContact.Rows.Count - 1; m++)
            {
                if (dgvContact.Rows[m].Cells[0].Value.ToString().Equals(Contact))
                {
                    MessageBox.Show("已存在！");
                    return;
                }
            }
            string[] row1 = new string[] { Contact, "Contacter" + i };
            dgvContact.Rows.Add(row1);
            i++;
        }
        //移除联系人
        private void btnDelContact_Click(object sender, EventArgs e)
        {
            dgvContact.Rows.RemoveAt(dgvContact.Rows.Count - 2);
            i--;
        }
        //添加附件
        private void btnAttachment_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                txtPath.Text = openFileDialog1.FileName;
            }
        }
        // 发送邮件后所处理的函数
        private static void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
        {
            try
            {
                if (e.Cancelled)
                {
                    MessageBox.Show("发送已取消！");
                }
                if (e.Error != null)
                {
                    MessageBox.Show("邮件发送失败！" + "
" + "技术信息:
" + e.Error.ToString(), "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
                else
                {
                    MessageBox.Show("邮件成功发出!", "恭喜!", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
            }
            catch (Exception Ex)
            {
                MessageBox.Show("邮件发送失败！" + "
" + "技术信息:
" + Ex.Message, "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　2013-12-19　　11:05:05