实时服务器上的 SMTP 类出错

Question

我有一个带有运行 .NET 3.5 的 ASP.NET MVC 后端的网站。在这个网站上，有一个使用 gmail 作为邮件服务发送电子邮件的脚本。该脚本在我的开发计算机上本地运行并发送邮件，但一旦我将其上传到实时服务器，它就会失败。目前它给我的唯一错误消息是（因为我告诉它，您将在下面看到）：

传输无法连接到服务器。

这是邮件程序脚本的代码：

using System.Net.Mail;
using System.Web.Mail;
using MailMessage = System.Web.Mail.MailMessage;

namespace MySite.Helpers
{
    public class GmailHelper
    {
        private readonly int _port = 465;
        private readonly string _accountName;
        private readonly string _password;

        public GmailHelper(string accountName, string password)
        {
            _accountName = accountName;
            _password = password;
        }
        public GmailHelper(string accountName, string password, int port)
        {
            _accountName = accountName;
            _password = password;
            _port = port;
        }
        public void Send(string from, string to, string subject, string body, bool isHtml)
        {
            Send(from, to, subject, body, isHtml, null);
        }

        public void Send(string from, string to, string subject, string body, bool isHtml, string[] attachments)
        {

            var mailMessage = new MailMessage

                                                          {
                                                              From = from,
                                                              To = to,
                                                              Subject = subject,
                                                              Body = body,
                                                              BodyFormat = isHtml ? MailFormat.Html : MailFormat.Text
                                                          };


            // Add attachments
            if (attachments != null)
            {
                foreach (var t in attachments)
                {
                    mailMessage.Attachments.Add(new Attachment(t));
                }
            }

            //  Authenticate
            mailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", 1);
            // Username for gmail - [email protected] for email for Google Apps
            mailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", _accountName);
            // Password for gmail account
            mailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", _password);
            // Google says to use 465 or 587.  I don't get an answer on 587 and 465 works - YMMV
            mailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserverport", _port.ToString());
            // STARTTLS 
            mailMessage.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpusessl", true);

            // assign outgoing gmail server
            SmtpMail.SmtpServer = "smtp.gmail.com";
            SmtpMail.Send(mailMessage);
        }
    }
}

它的名称是这样的：

[HttpPost]
public ActionResult Employment(EmploymentModel model, FormCollection collection)
{
    if (!ModelState.IsValid)
        return View(model);

    var results = new EmploymentViewModel();
    try
    {

        results.Position = model.Position;
        results.FirstName = model.FirstName;
        results.LastName = model.LastName;
        results.ContactPhone = model.ContactPhone;
        results.OtherPhone = model.OtherPhone;
        results.Address = model.Address;
        results.Email = model.Email;
        results.HsDiploma = model.HsDiploma.ToString();
        results.CollegeYears = model.CollegeYears;
        results.Skills = model.Skills;
        results.Employment = model.Employment;
        results.DateSent = DateTime.Now.ToString("MM/dd/yyyy HH:mm:ss");

        var gmail = new GmailHelper("[email protected]", "[*removed*]");

        var fromAddress = new MailAddress("[email protected]", "MySite");
        var toAddress = new MailAddress("[email protected]", "MySite Employment");
        var subject = string.Format("Employment Application for {0} {1}", model.FirstName, model.LastName);

        gmail.Send(fromAddress.Address, toAddress.Address, subject, EmployMailBody(results), false);
    }
    catch (Exception ex)
    {
        results.Sent = false;
        results.Title = "Oops, our mail drone seems to have malfunctioned!";
        results.Message = string.Format("We appologize, {0} {1}, but our email system has encountered an error and your email was not sent.</p>",
                results.FirstName, results.LastName);
        results.Message += Environment.NewLine + "<p>Please try your request later, or fax your résumé to our Corporate office.";
        results.Message += Environment.NewLine + JQueryHelpers.GenerateErrorField(ex.Message);

        return View("EmploymentSubmit", results);
    }
    results.Sent = true;
    results.Title = "Thank you for your submission!";
    results.Message = string.Format("Thank you for your interest in joining our team, {0} {1}!</p>", results.FirstName, results.LastName);
    results.Message += Environment.NewLine + "<p>We have successfully recieved your information and will contact you shortly at the number your have provided.";

    return View("EmploymentSubmit", results);
}

我 99% 确信它在网站上发布之前就可以正常工作，但我可能会弄错，因为自从我必须更新网站以来，已经有一个月左右的时间了。

我是否可以采取一些额外的步骤来“更好地”调试这个问题以追踪根本问题，或者我是否意外地在某个地方搞砸了我的代码？

谢谢！

EDIT1

所以我更新了类以严格使用 System.Net.Mail 。我成功地从我的开发机器发送了一条消息。然而，当我将该网站上传到我的服务器时，我收到了一条新的错误消息：

请求类型为“System.Net.Mail.SmtpPermission、System、Version=2.0.0.0、Culture=neutral、PublicKeyToken= 的权限” b77a5c561934e089' 失败。

该网站由 godaddy.com 托管，有些人在搜索后似乎 godaddy 只允许通过他们的 smtp 服务器进行中继。看来我必须更换托管提供商才能使其正常工作。

谢谢！

EDIT2

我从 godaddy 转移到 gmail 的原因最初是当我安装此脚本时，电子邮件将需要 15 到 45 分钟才能到达目的地框。这可能是我之前使用的已弃用的代码，但无论哪种方式，它现在都在几秒钟内被调度并到达，正如它应该的那样。这是我的 GoDaddy 帮助程序类，以防它对某人有帮助：

public class GoDaddyHelperNet
{
    private readonly int _port = 25;
    private readonly MailAddress _accountName;
    private readonly string _password;
    private readonly string _host = "relay-hosting.secureserver.net";

    public GoDaddyHelperNet(MailAddress accountName, string password)
    {
        _accountName = accountName;
        _password = password;
    }
    public GoDaddyHelperNet(MailAddress accountName, string password, int port)
    {
        _accountName = accountName;
        _password = password;
        _port = port;
    }
    public GoDaddyHelperNet(MailAddress accountName, string password, int port, string host)
    {
        _accountName = accountName;
        _password = password;
        _port = port;
        _host = host;
    }
    public void Send(MailAddress to, string subject, string body, bool isHtml)
    {
        Send(_accountName, to, subject, body, isHtml);
    }

    public void Send(MailAddress from, MailAddress to, string subject, string body, bool isHtml)
    {
        var smtp = new SmtpClient
                       {
                           Host = _host,
                           Port = _port,
                           EnableSsl = false,
                           DeliveryMethod = SmtpDeliveryMethod.Network,
                           UseDefaultCredentials = false,
                           Credentials = new NetworkCredential(from.Address, _password),
                           Timeout = 15000
                       };

        using (var message = new System.Net.Mail.MailMessage(from.Address, to.Address)
                     {
                         Subject = subject,
                         Body = body,
                     })

            smtp.Send(message);
    }
}

Answer 1

可能有防火墙规则或其他网络设备阻止了您。验证您是否可以从 Web 服务器远程登录到 Gmail 服务器并且可以发送电子邮件。

http://www.wikihow.com/Send-Email-Using-Telnet

如果不能，您可能需要与您的网络管理员联系。我大约一半的客户网络服务器上都有这样的电子邮件问题。

Answer 2

Gmail 对 SMTP 中继有很多限制。 IIRC 每天的收件人总数不超过 100 人。每条消息的收件人也有限制。消息/附件大小的限制。如果您超出限制或 Gmail 认为您看起来像垃圾邮件艺术家，他们的 SMTP 服务器可能会拒绝连接一天左右。