亚马逊SES停止工作

Question

亚马逊SES停止工作

asp.netamazon-web-servicessmtpamazon-ses

16

我设置了亚马逊SES，最初几个小时它能正常工作，但突然停止了。发送的所有电子邮件和我们的域名都已经得到验证。我们不会发送大量的电子邮件 - 每天仅有几百封。每当我对web.config进行更改时，似乎都可以让它再次工作2-3小时。例如，它停止工作，所以我将端口587切换到25，然后它开始工作了2-3个小时，然后停止了。然后我又切换回587，同样的事情发生了。一旦它停止工作，就不会自动重新启动。它正在运行两台负载均衡服务器上，asp.net框架v2.0，IIS 7.5。这是我正在使用的代码：

web.config:

<system.net>
  <mailSettings>
    <smtp deliveryMethod="Network" from="no-reply@ourdomain.com">
      <network defaultCredentials="false" host="email-smtp.us-east-1.amazonaws.com" userName="***" password="***" port="587" />
    </smtp>
  </mailSettings>
</system.net>

c# 代码：

var smtpClient = new SmtpClient() { EnableSsl = true };

var mailMessage =
    new MailMessage(fromAddress, toAddress, subject, body)
    {
        IsBodyHtml = true
    };

smtpClient.Send(mailMessage);

这里是我一直收到的两个错误：

The following exception was thrown by the web event provider '(null)' in the application '/' (in an application lifetime a maximum of one exception will be logged per provider instance):

System.Web.HttpException: Unable to send out an e-mail to the SMTP server. Please ensure that the server specified in the <smtpMail> section is valid. ---> System.Net.Mail.SmtpException: Failure sending mail. ---> System.IO.IOException: Received an unexpected EOF or 0 bytes from the transport stream.
   at System.Net.FixedSizeReader.ReadPacket(Byte[] buffer, Int32 offset, Int32 count)
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Threading.ExecutionContext.runTryCode(Object userData)
   at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
   at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
   at System.Net.Mail.SmtpConnection.Flush()
   at System.Net.Mail.ReadLinesCommand.Send(SmtpConnection conn)
   at System.Net.Mail.SmtpConnection.GetConnection(String host, Int32 port)
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   --- End of inner exception stack trace ---
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   at System.Web.Management.MailWebEventProvider.SendMail(MailMessage msg)
   --- End of inner exception stack trace ---
   at System.Web.Management.MailWebEventProvider.SendMail(MailMessage msg)
   at System.Web.Management.SimpleMailWebEventProvider.SendMessageInternal(WebBaseEventCollection events, Int32 notificationSequence, Int32 begin, DateTime lastFlush, Int32 discardedSinceLastFlush, Int32 eventsInBuffer, Int32 messageSequence, Int32 messagesInNotification, Int32 eventsInNotification, Int32 eventsLostDueToMessageLimit)
   at System.Web.Management.SimpleMailWebEventProvider.SendMessage(WebBaseEvent eventRaised)
   at *****.Global.SimpleMailWithSslWebEventProvider.ProcessEvent(WebBaseEvent raisedEvent)
   at System.Web.Management.WebBaseEvent.RaiseInternal(WebBaseEvent eventRaised, ArrayList firingRuleInfos, Int32 index0, Int32 index1)

The following exception was thrown by the web event provider '(null)' in the application '/' (in an application lifetime a maximum of one exception will be logged per provider instance):

System.Web.HttpException: Unable to send out an e-mail to the SMTP server. Please ensure that the server specified in the <smtpMail> section is valid. ---> System.Net.Mail.SmtpException: Service not available, closing transmission channel. The server response was: Timeout waiting for data from client.
   at System.Net.Mail.MailCommand.CheckResponse(SmtpStatusCode statusCode, String response)
   at System.Net.Mail.SmtpTransport.SendMail(MailAddress sender, MailAddressCollection recipients, String deliveryNotify, SmtpFailedRecipientException& exception)
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   at System.Web.Management.MailWebEventProvider.SendMail(MailMessage msg)
   --- End of inner exception stack trace ---
   at System.Web.Management.MailWebEventProvider.SendMail(MailMessage msg)
   at System.Web.Management.SimpleMailWebEventProvider.SendMessageInternal(WebBaseEventCollection events, Int32 notificationSequence, Int32 begin, DateTime lastFlush, Int32 discardedSinceLastFlush, Int32 eventsInBuffer, Int32 messageSequence, Int32 messagesInNotification, Int32 eventsInNotification, Int32 eventsLostDueToMessageLimit)
   at System.Web.Management.SimpleMailWebEventProvider.SendMessage(WebBaseEvent eventRaised)
   at *****.Global.SimpleMailWithSslWebEventProvider.ProcessEvent(WebBaseEvent raisedEvent)
   at System.Web.Management.WebBaseEvent.RaiseInternal(WebBaseEvent eventRaised, ArrayList firingRuleInfos, Int32 index0, Int32 index1)

我在亚马逊论坛上尝试寻求帮助，但没有成功。似乎有些东西正在干扰连接，但我不知道是什么。有任何想法吗？谢谢。

- StronglyTyped

3个回答

2

尽管此问题特定于 .NET v2.0，但我最近在 .NET v4.5 上也遇到了此问题。即使在 SMTP 客户端周围添加了 "using"（如早期帖子中建议的那样），我仍然会间歇性地收到此错误。经过多个小时的研究，我发现 AWS 支持 STARTTLS 端口（2587; http://docs.aws.amazon.com/ses/latest/DeveloperGuide/smtp-connect.html），并且在微软的非常小的字体中，当 SMTP 客户端的 "EnableSsl" 设为 true 时，客户端会期望一个 STARTTLS 会话 (https://msdn.microsoft.com/en-us/library/system.net.mail.smtpclient.enablessl(v=vs.110).aspx)。因此，在将我的端口更新为 2587并将 SmtpClient 包含在 "using {}" 中之后，我成功发送了约 20k 封电子邮件，而没有再次出现错误。

因此，工作配置如下:

<system.net>
  <mailSettings>
    <smtp deliveryMethod="Network">
      <network host="email-smtp.us-west-2.amazonaws.com" port="2587" enableSsl="true" password="password" />
    </smtp>
  </mailSettings>
</system.net>

需要说明的是，我仍然不完全理解 AWS 或 .NET SMTP 客户端的真正配置情况，因此这还有些间接性。

- Grady G Cooper

0

我也在使用AWS SES服务

 smtp deliveryMethod="Network" from="XXXXXXX@ZXXX.com"
    network enableSsl="true" host="email-smtp.us-east-1.amazonaws.com" userName="******" password="*********" port="25" 
 smtp

Hope this works for you.

- sbmandav

1

你的代码与我的唯一区别是：enableSsl="true"。该属性在我使用的框架 v2.0 的配置中不受支持，但是你可以看到它被添加到我的 c# 代码中初始化 SmtpClient 对象时。 - StronglyTyped

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- Steffen Opel · Accepted Answer

听起来确实是个棘手的问题 - 我不完全确定，但你似乎忘记释放SMTP客户端，而这在更改为VPC实例后发送电子邮件通常非常缓慢中已经提到，会导致你看到的错误:

当我没有释放SmtpClient时，我得到了错误...

'Service not available, closing transmission channel. The server response was: Timeout waiting for data from client.'

这实际上可以解释间歇性问题的原因，即根据执行的代码路径，此问题可能会触发SMTP连接Amazon SES挂起，这显然可以通过切换到另一个端口来解决，意味着连接被重置 - 这也是SmtpClient.Dispose Method所确保的:

向SMTP服务器发送QUIT消息，优雅地结束TCP连接，并释放当前实例SmtpClient类使用的所有资源。

因此，一个合适的模式应该是使用using语句，如入门指南Amazon SES和.NET所示：

  String username = "SMTP-USERNAME";  // Replace with your SMTP username.
  String password = "SMTP-PASSWORD";  // Replace with your SMTP password.
  String host = "email-smtp.us-east-1.amazonaws.com";
  int port = 25;

  using (var client = new System.Net.Mail.SmtpClient(host, port))
  {
    client.Credentials = new System.Net.NetworkCredential(username, password);
    client.EnableSsl = true;

    client.Send
    (
              "FROM@EXAMPLE.COM",  // Replace with the sender address.
              "TO@EXAMPLE.COM",    // Replace with the recipient address.
              "Testing Amazon SES through SMTP",              
              "This email was delivered through Amazon SES via the SMTP end point."
    );
  }

请注意示例使用的是端口25，由于通常暗示着发送限制，我强烈建议避免使用该端口。请见下面的附录以获取有关相关亚马逊EC2限制的详细信息。

祝你好运！

附录

亚马逊EC2上的25号端口限制

您可能已经意识到这一点（我实际上不认为这是一个问题），但是亚马逊EC2 对通过端口25发送的电子邮件施加默认的发送限制，并在您试图超过这些限制时限制出站连接，即使使用Amazon SES 也同样适用，请参阅Amazon SES SMTP Issues：

您从Amazon EC2实例通过端口25发送到Amazon SES，而您无法达到Amazon SES的发送限制或者您正在接收超时错误 — Amazon SES EC2 对通过端口25发送的电子邮件施加默认的发送限制，并在您试图超过这些限制时限制出站连接。要去除这些限制，请提交一个请求，以去除电子邮件发送限制。您还可以通过端口465或端口587连接到 Amazon SES，这两个端口都没有被限制。

因此，在您的测试/切换方案中我会删除端口25，并仅使用端口465/587以避免错误（正如引用所述，您也可以请求去除这个限制，但需要几个小时，而且最好一开始就避免使用端口25）- 确实有点不幸，一些官方Amazon SES示例在使用端口25时甚至没有提到这个容易触发的问题。