.net (c#)实现发送外部邮件的实例

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.Net.Mail;

public partial class testSendMail : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string strFrom = "[e-mail]";
        string strTo = "[e-mail]";
        string strSubject = "webtest";
        string strBody = "测试";
        System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(strFrom, strTo, strSubject, strBody);
        message.BodyEncoding = System.Text.Encoding.UTF8;
        message.IsBodyHtml = true;

        SendSMTPEMail("smtp.126.com", "[e-mail]", "111111", message);

    }
    public void SendSMTPEMail(string strSmtpServer, string strFrom, string strFromPass, MailMessage message)
    {
        try
        {
            SmtpClient client = new SmtpClient(strSmtpServer);
            client.UseDefaultCredentials = true;
            client.Credentials = new System.Net.NetworkCredential(strFrom, strFromPass);
            client.DeliveryMethod = SmtpDeliveryMethod.Network;
            
            client.Send(message);
        }
        catch (Exception ex)
        {
            throw new Exception(ex.Message);
        }
    }
}

//发送邮件的通用方法整理

 public void SendEmail(string subject, string body, params string[] tos)
        {
            string host = _commonAppService.GetSettingValue("Common_EmailHost");
            string fromName = _commonAppService.GetSettingValue("Common_EmailFromName");
            string from = _commonAppService.GetSettingValue("Common_NoreplyEmailUserName");
            string password = _commonAppService.GetSettingValue("Common_NoreplyEmailPassword");

            MailMessage message = new MailMessage();
            message.From = new MailAddress(from, fromName);
            foreach (var to in tos)
            {
                message.To.Add(to);
            }
            message.Subject = subject;
            message.Body = body;
            message.IsBodyHtml = true;

            SmtpClient smtpClient = new SmtpClient();
            smtpClient.UseDefaultCredentials = true;
            smtpClient.Credentials = new NetworkCredential(from, password);
            smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;
            smtpClient.Host = host;

//如果是发送邮箱是gmail要加上这个代码否则邮件无法发送成功
            if (smtpClient.Host == "smtp.gmail.com")
            {
                smtpClient.EnableSsl = true;
                smtpClient.Port = 587;
            }

            try
            {
                smtpClient.Send(message);
            }
            catch
            {
                AssertHelper.NoPass(true, R.Package, R.Keys.K邮件_错误信息_邮件发送失败);
            }
        }

注意：
1、确保strFrom的值和strSmtpServer的值一致，否之会报Send Error:不允许使用邮箱名称。 服务器响应为: You are not authorized to send mail, authentication is required。的错误
2、确保用于发送邮件的邮箱不是刚注册的邮箱，而要用有提供SMTP服务的邮箱的帐号和密码，否则会报邮箱不可以用的错误

引用

为何新申请的邮箱不能用客户端？
　　目前免费邮箱新注册的用户不支持直接开通smtp、pop3的服务，之前已开通客户端功能的老用户不受影响。如果需要使用该功能，您可开通增值服务邮箱伴侣或随身邮 ，即可同时获取poo功能。
----------------
新注册的用户付费才能使用...

3、下面两句的书写的顺序不能颠倒

client.UseDefaultCredentials = true;
client.Credentials = new System.Net.NetworkCredential(strFrom, strFromPass);

否则会报这样的错误

引用

Send Error:不允许使用邮箱名称。 服务器响应为: You are not authorized to send mail, authentication is required。就是说没有通过登录认证

4、注意126的域名是smtp.126.com
163的域名是smtp.163.com