Amazon SES 停止工作

Question

我设置了 Amazon SES，它最初工作了几个小时，然后突然停止了。我发送的所有电子邮件以及我们的域都已通过验证。我们不会发送大量电子邮件 - 每天只有几百封。每当我对 web.config 进行更改时，它似乎允许它再次工作 2-3 小时。例如，它停止工作，所以我将端口 587 切换到 25，它开始工作 2-3 小时，然后停止。然后我切换回587，同样的事情发生了。一旦它停止工作，它似乎永远不会自行重新开始。它运行在两台负载平衡服务器上，asp.net framework 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);

这是我收到的两个错误：

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)

我试图在亚马逊论坛上寻求帮助，但没有任何运气。似乎有什么东西干扰了连接，但我不知道是什么。有任何想法吗？谢谢。

Answer 1

虽然这个问题是 .NET v2.0 特有的，但我最近在 .NET v4.5 上也遇到了这个问题。即使在添加了 using around SMTP client（如之前的帖子中所建议的那样）之后，我仍然间歇性地收到此错误。经过数小时的研究，我发现了 AWS 对 STARTTLS 端口（2587；http://docs.aws.amazon.com/ses/latest/DeveloperGuide/smtp-connect.html）的支持，并且在非常精美的字样中，Microsoft 声明当 SMTP 客户端上的“EnableSsl”为真时，客户端需要一个 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 包围在“使用 {}”中后，我能够成功发送大约 20k 封电子邮件而不会重现错误。

因此，工作配置将是：

<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>

一个免责声明是，我仍然不完全了解 AWS 或 .NET SMTP 客户端的真实配置，所以这仍然有点间接。

Answer 2

这听起来确实是一个棘手的问题 - 我对此不是 100% 肯定，但您似乎错过了处置 SMTP 客户端，Sending email is often very slow after changing to VPC instance 中提到会导致您看到的错误：

当我不处理 SmtpClient 时，我收到错误...

'服务不可用，正在关闭传输通道。服务器 响应是：等待来自客户端的数据超时。'

这实际上是对间歇性问题的一个很好的解释，即根据执行的代码路径，此问题可能会触发与Amazon SES 的 SMTP 连接挂起，这显然可以通过切换到另一个端口来解决，这意味着连接被重置- 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，并释放当前实例使用的所有资源 SmtpClient 类。

因此，适当的模式是促进using Statement，如Getting Started with Amazon SES and .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，该示例使用端口 25，由于通常隐含的发送限制，我强烈建议您避免使用该端口，有关各个 Amazon EC2 限制的详细信息，请参阅下面的附录。

祝你好运！

---

附录

Amazon EC2 在端口 25 上节流

您可能知道这一点（实际上我认为这不是问题），但Amazon EC2 对通过端口 25 发送的电子邮件施加默认发送限制，如果您尝试超过这些限制，则会限制出站连接限制 在使用Amazon SES 时仍然适用，请参阅Amazon SES SMTP Issues：

您正在通过端口 25 从 Amazon EC2 实例发送到 Amazon SES 并且您无法达到您的 Amazon SES 发送限制，或者您正在 接收超时 — Amazon SES EC2 对 通过端口 25 发送的电子邮件并限制出站连接，如果您 试图超越这些限制。要取消这些限制，请提交 Request to Remove Email Sending Limitations。您还可以连接到 Amazon SES 通过端口 465 或端口 587，这两个端口都没有受到限制。

因此，我会从您的测试/切换方案中删除端口 25，而仅使用端口 465/587 以避免虚假线索（如引用的那样，您也可以请求删除此限制，但这需要几个小时，似乎最好首先避免使用端口 25）- 有点不幸的是，几个官方的 Amazon SES 示例都在使用端口 25，甚至没有提及这个容易触发的问题。

Answer 3

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

希望这对你有用。