在asp.net (C#)中发送电子邮件时遇到问题。使用gmail或hotmail配置时不会出现此问题

using System.Net;
using System.Net.Mail;

public void SendEmail(string to, string subject, string body)
{
    string smtpServer = "smtp.gmail.com";
    int smtpPort = 587;
    string username = "your-email@gmail.com";
    string password = "your-password";

    using (SmtpClient client = new SmtpClient(smtpServer, smtpPort))
    {
        client.EnableSsl = true;
        client.Credentials = new NetworkCredential(username, password);

        MailMessage message = new MailMessage();
        message.From = new MailAddress(username);
        message.To.Add(to);
        message.Subject = subject;
        message.Body = body;

        client.Send(message);
    }
}