在按钮单击ASP.NET后发送电子邮件，而不等待操作完成执行

protected async void Button_Click(object sender, EventArgs e)
{
    await SendEmailAsync();
}

private async Task SendEmailAsync()
{
    string smtpServer = "SMTP服务器地址";
    int smtpPort = 25;
    string smtpUsername = "邮箱地址";
    string smtpPassword = "密码";
    string fromEmail = "发件人邮箱";
    string toEmail = "收件人邮箱";
    string subject = "邮件主题";
    string body = "邮件内容";

    using (SmtpClient smtpClient = new SmtpClient(smtpServer, smtpPort))
    {
        smtpClient.Credentials = new NetworkCredential(smtpUsername, smtpPassword);
        smtpClient.EnableSsl = true;

        MailMessage mailMessage = new MailMessage(fromEmail, toEmail, subject, body);

        await smtpClient.SendMailAsync(mailMessage);
    }
}