如何解决谷歌邮件错误“SMTP 服务器需要安全连接或客户端未通过身份验证”？

Question

MailMessage mailMessage = new MailMessage();
mailMessage.From = new MailAddress("sendemail@gmail.com");
mailMessage.To.Add("receiveemail@mydomain.com");
mailMessage.Subject = "New Enquiry" ;

mailMessage.Body = "<b>Sender Name : </b>" + txt_name.Text + "<br/>"
    + "<b>Contact Number : </b>" + txt_number.Text + "<br/>"
    + "<b>Sender Email : </b>" + txt_email.Text + "<br/>"
    + "<b>Details : </b>" + txt_message.Text;
mailMessage.IsBodyHtml = true;


SmtpClient smtpClient = new SmtpClient("smtp.gmail.com", 587);
smtpClient.EnableSsl = true;
smtpClient.UseDefaultCredentials = false;
smtpClient.Credentials = 
    new System.Net.NetworkCredential("sendemail@gmail.com", "Password");
smtpClient.Send(mailMessage);

Response.Write("<Script>alert('Thanks for contact us,our team will be contact you as soon as possible')</Script>");

txt_name.Text = "";
txt_email.Text = "";
txt_number.Text = "";
txt_message.Text = "";

This is my ASP.NET C# code for sending emails through the website's contact us page. But Google has discontinued the less secure app access option as of May 30, 2022 due to security reasons. So now I'm not able to send emails using the above code.

Less Secure app access snapshot:

How can I deal with this so I can send email again?

Answer 1

https://support.google.com/accounts/answer/6010255

from May 30, 2022, ​​Google no longer supports the use of third-party apps or devices which ask you to sign in to your Google Account using only your username and password.

Important: This deadline does not apply to Google Workspace or Google Cloud Identity customers. The enforcement date for these customers will be announced on the Workspace blog at a later date.

Now you can manage Apps password:

1. Go to Gmail account settings , and click on security tab
2. add 2 step verification (if you don't have)
3. click on "App Password"
4. select application device or add new one
5. you will get new password to use in your app

change the email password in your app , and try to send emails