邮件发送

前台界面：

后台代码：（不同的邮件主机可能会需要端口号）

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.Threading;

namespace Mail
{
    public partial class SendMail : Form
    {
        public SendMail()
        {
            InitializeComponent();
        }

        string[] FileNames
        {
            get;
            set;
        }

        //发送邮件按钮
        private void btnSend_Click(object sender, EventArgs e)
        {
            string to = tbTo.Text;
            string from = "xxx@sina.com";
            string subject = tbTheme.Text;
            string content = @tbContent.Text;
            MailMessage msg = new MailMessage(from, to, subject, content);
            msg.IsBodyHtml = true;

            //Thread threadMail = new Thread(new  ParameterizedThreadStart(SendEmail));
            //threadMail.Start(msg);
            ThreadPool.SetMaxThreads(0, 0);
            ThreadPool.QueueUserWorkItem(new WaitCallback(SendEmail), msg);
            btnSend.Enabled = false;
        }

        /// <summary>
        /// 异步发邮件
        /// </summary>
        /// <param name="message"></param>
        private void SendEmail(object message)
        {
            SmtpClient client = new SmtpClient("smtp.sina.com");//有可能需要端口号
            client.Credentials = new NetworkCredential("xxx@sina.com", "***");
            MailMessage msg = message as MailMessage;
            if (FileNames != null)
            {
                foreach (string fileName in FileNames)
                {
                    Attachment atta = new Attachment(fileName);
                    msg.Attachments.Add(atta);
                }
            }
            client.Send(msg);
            this.Invoke(new ButtonEnableDelegate(EnableControl), new object[] { btnSend });
            //Thread.CurrentThread.Abort();
        }

        delegate void ButtonEnableDelegate(Control control);

        private void EnableControl(Control control)
        {
            control.Enabled = true;
        }

        //选择附件
        private void btnAttach_Click(object sender, EventArgs e)
        {
            OpenFileDialog dia = new OpenFileDialog();
            dia.Filter = "JPEG (*.jpg)|*.jpg|PNG (*.png)|*.png";
            dia.RestoreDirectory = true;
            dia.Multiselect = true;
            if (dia.ShowDialog() == DialogResult.OK)
            {
                if (dia.FileNames.Length == 0)
                {
                    return;
                }
                this.FileNames = dia.FileNames;
                this.tbAttach.Text = string.Empty;
                foreach (string fileName in dia.FileNames)
                {
                    tbAttach.Text += fileName.Substring(fileName.LastIndexOf('\\')+1) + ";";
                }
            }
        }
    }
}