我使用带有 pdf 附件的商务电子邮件发送电子邮件，该附件是我在运行时使用字符串数据生成的

Question

但它说“SMTP 服务器需要安全连接，或者客户端未经过身份验证。服务器响应是：5.7.0 需要身份验证。了解更多信息”

或“发送邮件失败。”

我的代码如下：

protected void BtnSendEmail_Click(对象发件人, EventArgs e) { Send_Email("[email protected]","这是一封带有附件的邮件！","你好，祝你有美好的一天。我已经给你发送了一封带有附件的电子邮件！"); }

protected string Bind_Invoice()
{
    string op = null;
    try
    {
        con = new SqlConnection(CommonClass.Get_DB_Path);
        con.Open();
        cmd = new SqlCommand("BIND_PURCHASE_INVOICE", con);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.CommandTimeout = 10000;
        cmd.Parameters.AddWithValue("@USER", Session["username"].ToString());
        SqlParameter RuturnValue = new SqlParameter("@RETVAL", SqlDbType.VarChar, 18000);
        RuturnValue.Direction = ParameterDirection.Output;
        cmd.Parameters.Add(RuturnValue);
        cmd.ExecuteNonQuery();
        op = cmd.Parameters["@RETVAL"].Value.ToString();
        cmd.Dispose();
        con.Close();

    }
    catch (Exception ex)
    {
        if (ex.Message != null)
        {
            op = ex.Message;
            con.Close();
        }
    }
    return op;
}

protected void Send_Email(string ToAddress, string MailSubject, string MailBody)
{
    try
    {
        MailMessage message = new MailMessage();
        message.To.Add(ToAddress);// Email-ID of Receiver  
        message.Subject = MailSubject;// Subject of Email  
        message.From = new System.Net.Mail.MailAddress("MYUSERNAME");// Email-ID of Sender  
        message.IsBodyHtml = true;

        string PDFdata = Bind_Invoice();
        MemoryStream file = new MemoryStream(PDFGenerate(PDFdata, Server.MapPath("img/bg.jpg")).ToArray());

        file.Seek(0, SeekOrigin.Begin);
        Attachment data = new Attachment(file, "RunTime_Attachment.pdf", "application/pdf");
        ContentDisposition disposition = data.ContentDisposition;
        disposition.CreationDate = System.DateTime.Now;
        disposition.ModificationDate = System.DateTime.Now;
        disposition.DispositionType = DispositionTypeNames.Attachment;
        message.Attachments.Add(data);//Attach the file  

        message.Body = MailBody;
        SmtpClient SmtpMail = new SmtpClient();
        SmtpMail.Host = "MY HOST ADDRESS";//name or IP-Address of Host used for SMTP transactions  
        SmtpMail.Port = 465;//Port for sending the mail  
        SmtpMail.Credentials = new System.Net.NetworkCredential("MYUSERNAME", "MYPASS");//username/password of network, if apply  
        SmtpMail.DeliveryMethod = SmtpDeliveryMethod.Network;
        SmtpMail.EnableSsl = true;
        SmtpMail.UseDefaultCredentials = false;
        SmtpMail.ServicePoint.MaxIdleTime = 0;
        SmtpMail.ServicePoint.SetTcpKeepAlive(true, 2000, 2000);
        message.BodyEncoding = Encoding.Default;
        message.Priority = MailPriority.High;
        SmtpMail.Send(message); //Smtpclient to send the mail message  
        Response.Write("Email has been sent !");
    }
    catch (Exception ex)
    { 
        Response.Write("Failed !"); 
    } 
}

private MemoryStream PDFGenerate(string message, string ImagePath)
{
    MemoryStream output = new MemoryStream();
    Document pdfDoc = new Document(PageSize.A4, 25, 10, 25, 10);
    PdfWriter pdfWriter = PdfWriter.GetInstance(pdfDoc, output);
    pdfDoc.Open();
    Paragraph Text = new Paragraph(message);
    pdfDoc.Add(Text);
    byte[] file;
    file = System.IO.File.ReadAllBytes(ImagePath);
    iTextSharp.text.Image jpg = iTextSharp.text.Image.GetInstance(file);
    jpg.ScaleToFit(550F, 200F);
    pdfDoc.Add(jpg);
    pdfWriter.CloseStream = false;
    //pdfDoc.Close();
    output.Position = 0;
    return output;
}

任何帮助将不胜感激......

Answer 1

如果您遇到身份验证失败，这应该是与附件不同的问题。许多提供商（尤其是 Google）现在需要双因素身份验证，如果您使用这些提供商之一来发送电子邮件，则可能必须首先解决这个问题。对于 Gmail，您基本上必须获取应用程序登录时使用的密码，而不是普通密码。这神奇地满足了两因素要求并允许您发送电子邮件。以下是 Google 支持论坛的相关讨论：

https://support.google.com/mail/thread/146949535/the-server-response-was-5-7-0-authentication-required?hl=en