以下有2種方法：

第一種:

using System;
using System.Net.Mail;

//當時測試的是QQ郵箱
class TestMail
{
    static void Main(string[] args)
    {
        string mailContent = "郵件內容";
        MailMessage msg = new System.Net.Mail.MailMessage();
        msg.To.Add("[email protected],[email protected]"); //收件人

        //發件人信息
        msg.From = new
 
 MailAddress("[email protected]", "發送人姓名", System.Text.Encoding.UTF8);
        msg.Subject = "這是測試郵件";   //郵件標題
        msg.SubjectEncoding = System.Text.Encoding.UTF8;    //標題編碼
        msg.Body = mailContent; //郵件主體
        msg.BodyEncoding = System.Text.Encoding.UTF8;
        msg.IsBodyHtml = true;  //是否HTML
 

        msg.Priority = MailPriority.High;   //優先級
        SmtpClient client = new SmtpClient();
        //註意：下面的這個密碼是授權碼，不是你登錄QQ的密碼，查看方法：QQ郵箱---設置裏面
        client.Credentials = new System.Net.NetworkCredential("[email protected]", "asdfghjkl");
        client.EnableSsl = true;
        client.Port = 587
 
;   //443
        client.Host = "smtp.qq.com";//mail.adient.com
        object userState = msg;
        try
        {
            client.Send(msg);
            //MessageBox.Show("發送成功");
        }
       catch (Exception ex)
       {
            //MessageBox.Show(ex.Message, "發送郵件出錯");
       }
    }
}

第二種：

//當時測試的是outlook 延鋒的郵箱
using System.Net.Mail;

namespace ConsoleApplication11
{
    class Program
    {
        static void Main(string[] args)
        {
            MailMessage mail = new MailMessage();
            //設置郵件的標題            
            mail.Subject = "測試郵件";
            //設置郵件的發件人            
            //mail.From = new MailAddress("[email protected]", "Xiao_1006");
            //發件人的郵箱地址，後面參數 張猛：收件人看到的發件人的名稱
            mail.From = new MailAddress("[email protected]", "張猛");
            //設置郵件的收件人，ZMENG沒有什麽用        
            mail.To.Add("[email protected],[email protected]");
            //設置郵件的抄送人             
         //   mail.CC.Add(new MailAddress("[email protected]", "Nick"));
            //設置郵件的內容             
            mail.Body = "就是測試用111";
            mail.BodyEncoding = System.Text.Encoding.UTF8;
            mail.IsBodyHtml = true;
            mail.Priority = MailPriority.Normal;
            mail.DeliveryNotificationOptions = DeliveryNotificationOptions.OnSuccess;
            SmtpClient client = new SmtpClient();
            //郵件服務器的名稱，要問對方公司才知道
            client.Host = "smtp.ga.adient.com";
            //發郵件的端口號，要問對方公司才知道
            client.Port = 25;
            client.UseDefaultCredentials = false;
            //client.Credentials = new System.Net.NetworkCredential("[email protected]", "Xiao_1006");
            //發件人的賬號和密碼
            client.Credentials = new System.Net.NetworkCredential("[email protected]", "Yfas123");
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            client.Send(mail);
        }
    }
}

用C#發郵件