c# - 在 C# .net 中发送邮件失败

Question

我发送电子邮件的代码在 psat 两周内正常工作。但是现在它显示了类似

的错误

Failure Sending Mail.

我不知道为什么会出现这个问题。上周放了一些新的防火墙策略，是不是因为这个问题才出现？我该怎么办？

这是我的代码:

 protected void Button1_Click(object sender, EventArgs e)
    {
        try
        {
            if (TextBox1.Text == "")
            {

                string alertmessage = "";
                alertmessage = "Email ID. cannot be blank ";
                this.CreateMessageAlert(this, alertmessage, "alertKey");
                TextBox1.Focus();
            }
            else if (TextBox2.Text == "")
            {

                string alertmessage = "";
                alertmessage = "CC To cannot be blank ";
                this.CreateMessageAlert(this, alertmessage, "alertKey");
                TextBox2.Focus();
            }
            else if (TextBox3.Text == "")
            {

                string alertmessage = "";
                alertmessage = "Subject cannot be blank ";
                this.CreateMessageAlert(this, alertmessage, "alertKey");
                TextBox3.Focus();
            }
            else if (TextBox4.Text == "")
            {

                string alertmessage = "";
                alertmessage = "Message Body cannot be blank ";
                this.CreateMessageAlert(this, alertmessage, "alertKey");
                TextBox4.Focus();
            }
            //else if (upSignature.FileName == "")
            //{
            //    ctr = 1;
            //    string alertmessage = "";
            //    alertmessage = "Attachment  Missing...";
            //    this.CreateMessageAlert(this, alertmessage, "alertKey");
            //    upSignature.Focus();
            //}

            else
            {


                string photo = "Enquiry" + Session["MRNO"].ToString() + FileUpload1.FileName;
                string strpath = Request.MapPath("~/");
                FileUpload1.SaveAs(strpath + "/Enquiry/" + photo);


                try
                {
                    MailMessage mail = new MailMessage();
                    mail.To.Add(new MailAddress(TextBox1.Text.Trim()));
                    mail.From = new MailAddress("XXXXXXX");
                    mail.Subject = "Enquiry for MRNO " + " " + " " + Session["MRNO"].ToString() + " " + " " + "Reg.";
                    mail.CC.Add(TextBox2.Text.Trim());
                    mail.Body = TextBox4.Text.Trim();

                        mail.Attachments.Add(new Attachment(FileUpload1.PostedFile.InputStream, FileUpload1.FileName));
                        mail.Attachments.Add(new Attachment(FileUpload2.PostedFile.InputStream, FileUpload2.FileName));

                    //Attachment attach = new Attachment(strpath + "/Enquiry/" + photo);
                    //mail.Attachments.Add(attach);


                    SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);

                    smtp.EnableSsl = true;

                    smtp.UseDefaultCredentials = false;
                    smtp.Credentials = new NetworkCredential("XXXXXX", "XXXXXXX");

                    smtp.Send(mail);

                    string alertmessage = "";
                    alertmessage = "Mail Has Been Sent";
                    this.CreateMessageAlert(this, alertmessage, "alertKey");


                    //   Page.RegisterStartupScript("close", "<script language=javascript>self.close();</script>");

                }
                catch (Exception ex)
                {
                    Response.Write(ex.Message);
                }
            }
        }
        catch (Exception ex1)
        {
            Response.Write(ex1.Message);
        }

    }

Answer 1

发送邮件需要开启587端口。就此与您的网络团队核实并确保它已打开