问使用Gmail和C#/VB.Net发送电子邮件不再有效

EN

try
     {
        MailMessage mail = new MailMessage();     //using System.Net.Mail namespace
        mail.To.Add("xyz@yahoo.com");             //Enter reciever's email address
        mail.From = new MailAddress("abc@gmail.com");  //Enter sender's email address
        mail.Subject = "Testing mail...";
        mail.Body = @"Lets-code ! Lets-code to make it simpler";
        mail.IsBodyHtml = true;                  //Body of mail supports html tags
        SmtpClient smtp = new SmtpClient();
        smtp.Host = "smtp.gmail.com";
        smtp.Port = 587;
        smtp.Credentials = new System.Net.NetworkCredential("abc@gmail.com", "pwd");
        // Your gmail username and password   
        smtp.EnableSsl = true;            //Gmail uses a encrypted connection
        smtp.Send(mail);
        Response.Write("Mail Sent Successfully");
    }

catch(Exception ex)
    {  
        Response.Write(ex.Message);
    }

Imports System.Net.Mail

Protected Sub btnSendEmail_Click(ByVal sender As Object, ByVal e As EventArgs)
  Dim mail As MailMessage =  New MailMessage() 
  mail.To.Add("receiversmail@gmail.com")
  mail.From = New MailAddress("yourmail@gmail.com")
  mail.Subject = "Email using Gmail"

  String Body = "Sending mail using Gmail's SMTP"
  mail.Body = Body

  mail.IsBodyHtml = True
  Dim smtp As SmtpClient =  New SmtpClient() 
  smtp.Host = "smtp.gmail.com" 
  smtp.Credentials = New System.Net.NetworkCredential
       ("yourmail@gmail.com","password")
  smtp.EnableSsl = True
  smtp.Port = 587
  smtp.EnableSsl = true
  smtp.Send(mail)
End Sub