public bool Send()
{
    try
    {
        SmtpClient smtp = new SmtpClient(this.Host!, (int)this.Port!) { Credentials = new NetworkCredential(this.User!, this.Password!), EnableSsl = true, UseDefaultCredentials = false };
        MailMessage message = new MailMessage(this.SenderAddress!, this.ReciverAddress!, this.Subject, this.Body) { From = new MailAddress(this.SenderAddress!, this.SenderName) };
        ServicePointManager.ServerCertificateValidationCallback = delegate (object obj, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        };
        smtp.Send(message);
        return true;
    }
    catch (Exception)
    {
        return false;
    }
}

public bool Send()
{
    try
    {
        SmtpClient smtp = new SmtpClient(this.Host!, (int)this.Port!) { Credentials = new NetworkCredential(this.User!, this.Password!), EnableSsl = true, UseDefaultCredentials = false };
        MailMessage message = new MailMessage(this.SenderAddress!, this.ReciverAddress!, this.Subject, this.Body) { From = new MailAddress(this.SenderAddress!, this.SenderName) };
        ServicePointManager.ServerCertificateValidationCallback = delegate (object obj, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        };
        smtp.Send(message);
        return true;
    }
    catch (Exception)
    {
        return false;
    }
}

public bool Send()
{
    try
    {
        smtp = new SmtpClient(this.Host, (int)this.Port);
        smtp.Credentials = new NetworkCredential(this.User,this.Password);
        smtp.EnableSsl = true;
        //smtp.UseDefaultCredentials = false;
        MailMessage message = new MailMessage(this.SenderAddress, this.ReciverAddress, this.Subject, this.Body) { From = new MailAddress(this.SenderAddress, this.SenderName) };
        ServicePointManager.ServerCertificateValidationCallback = delegate (object obj, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        };
        smtp.Send(message);
        return true;
    }
    catch (Exception)
    {
        return false;
    }
}

public bool UseDefaultCredentials
{
    get
    {
        if (!(transport.Credentials is SystemNetworkCredential))
        {
            return false;
        }

        return true;
    }
    set
    {
        if (InCall)
        {
            throw new InvalidOperationException(SR.GetString("SmtpInvalidOperationDuringSend"));
        }

        transport.Credentials = (value ? CredentialCache.DefaultNetworkCredentials : null);
    }
}

 //
 // 摘要:
 //     Gets or sets a System.Boolean value that controls whether the System.Net.CredentialCache.DefaultCredentials
 //     are sent with requests.
 //
 // 返回結(jié)果:
 //     true if the default credentials are used; otherwise false. The default value
 //     is false.
 //
 // 異常:
 //   T:System.InvalidOperationException:
 //     You cannot change the value of this property when an email is being sent.
 public bool UseDefaultCredentials
 {
     get;
     set;
 }