c# smtp邮件发送示例源码(带附件/支持中文)

【实例截图】

【核心代码】

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.IO;
using System.Net;

namespace SendEmail
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        //保存名称
        private string fileName = "";
        //文件操作
        FileStream fs = null;

        //设置Smtp协议
        SmtpClient smtpClient = null;
        //设置发信人地址 需要密码
        MailAddress AddressFrom = null;
        //设置收信人地址 不需要密码
        MailAddress AddressTo = null;
        //邮件信息
        MailMessage Message = null;

        //设置Smtp服务器信息
        private void SetSmtpClient(string serverHost, int Port)
        {
            smtpClient = new SmtpClient();
            //指定Smtp服务名
            //QQ:smtp.qq.com
            //sina：smtp.sina.cn
            smtpClient.Host = serverHost;
            smtpClient.Port = Port;
            smtpClient.Timeout = 0;
        }

        //验证发件人信息
        private void SetAddressFrom(string mailAddress, string mailPwd)
        {
            //创建服务器验证
            NetworkCredential networkCreadential_My = new NetworkCredential(mailAddress,mailPwd);
            //实例化发件人地址
            AddressFrom = new MailAddress(mailAddress,tbShowName.Text);
            //指定发件人信息 邮箱地址和密码
            smtpClient.Credentials = new NetworkCredential(AddressFrom.Address, mailPwd);

        }

        //发送
        private void btnSend_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("您确定要发送当前邮件吗？", "发送提示", MessageBoxButtons.YesNo, MessageBoxIcon.Question)==DialogResult.Yes)
            {
                try
                {
                    //设置Smtp服务器信息
                    SetSmtpClient("smtp."   cmbSmtp.Text   cmbHZ.Text, Convert.ToInt32(nudPort.Value));

                }
                catch (Exception err)
                {
                    MessageBox.Show("邮件发送失败，请确定Smtp服务器名是否正确!" "\n" "技术信息：" err.Message);
                    return;
                }
                try
                {
                    if (tbPwd.Text == "")
                    {
                        MessageBox.Show("对不起，需要密码验证，请输入密码！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                        tbPwd.Focus();
                        return;
                    }

                    //设置发送地址信息
                    SetAddressFrom(tbSendEmail.Text.Trim()   cmbSendHZ.Text, tbPwd.Text);
                }
                catch (Exception)
                {
                    MessageBox.Show("邮件发送失败，请确认发送邮箱地址和密码的正确性!");
                    return;
                }

                //message信息
                Message = new MailMessage();

                //发信人地址
                Message.From = AddressFrom;
                //收信人地址
                AddressTo = new MailAddress(tbReceiveEmail.Text.Trim()   cmbReceiveHZ.Text);
                //添加收信人地址
                Message.To.Add(AddressTo);

                //信息的主题
                Message.Subject = tbTitle.Text;
                //主题的编码方式
                Message.SubjectEncoding = System.Text.Encoding.UTF8;

                //邮件正文
                Message.Body = tbContent.Text;
                //邮件正文的编码
                Message.BodyEncoding = System.Text.Encoding.UTF8;

                //清除附件信息
                Message.Attachments.Clear();
                //添加附件
                if (tbAttachment.Text != "")
                {
                    Message.Attachments.Add(new Attachment(tbAttachment.Text.Trim()));
                }
                //发送
                smtpClient.SendAsync(Message, "000000");
                //发送完成回调函数
                smtpClient.SendCompleted  = new SendCompletedEventHandler(SendBack);

            }
        }

        //页面载入
        private void Form1_Load(object sender, EventArgs e)
        {
            //初始化下拉框
            cmbHZ.SelectedIndex = 0;
            cmbReceiveHZ.SelectedIndex = 0;
            cmbSendHZ.SelectedIndex = 0;
            cmbSmtp.SelectedIndex = 0;
        }

        //回调函数
        private void SendBack(object sender, AsyncCompletedEventArgs e)
        {
            MessageBox.Show("您的邮件已成功发送!","恭喜",MessageBoxButtons.OK,MessageBoxIcon.Information);
        }

        
        //选择附件
        private void btn_SelectAttach_Click(object sender, EventArgs e)
        {
            //打开文件对话框
            OpenFileDialog open = new OpenFileDialog();
            if (open.ShowDialog() == DialogResult.OK)
            {
                //保存选择的文件名
                fileName = open.SafeFileName;
                tbAttachment.Text = open.SafeFileName;
                
            }
        }

        //文本框变化事件
        private void tbAttachment_EditValueChanged(object sender, EventArgs e)
        {
            //判断时候可以上传
            if (CanAddAttachment(tbAttachment.Text))
            {
               //判断大小是否允许
                if (CanAddSize(tbAttachment.Text))
                {
                    lblState.Visible = true;
                    lblState.Text = "添加成功!";
                }
                else
                {
                    MessageBox.Show("上传的文件过大!");
                    btnSend.Enabled = false;
                    return;
                }
            }
            else
            {
                MessageBox.Show("不支持该格式的附件!");
                btnSend.Enabled = false;
                return;
            }
        }

        //判断附件类型是否合法
        private bool CanAddAttachment(string path)
        {
            //实例化文件操作对象
            fs = new FileStream(path, FileMode.Open);
            //设置允许添加的附件类型
            string[] allowExtensions = new string[] { ".jpg", ".jpeg", ".doc", ".docx", ".txt", ".excel",".rar",".zip"};
            //获取文件的后缀
            string name = System.IO.Path.GetExtension(fs.Name);
            for (int i = 0; i < allowExtensions.Length; i  )
            {
                if (name == allowExtensions[i])
                {
                    return true;
                }
            }
            fs.Flush();
            fs.Close();
            return false;
        }

        //获取文件大小
        private bool CanAddSize(string path)
        {
            double size = Convert.ToDouble(fs.Length) / 1024.0 / 1024.0;
            //设置最大为10M
            if (size > 10)
            {
                return false;
            }
            fs.Flush();
            fs.Close();
            return true;
        }


    }
}