private async Task <bool> SendMessageAsync(MtaQueuedMessage msg)
{
// Check that the message next attempt after has passed.
if (msg.AttemptSendAfterUtc > DateTime.UtcNow)
{
await RabbitMqOutboundQueueManager.Enqueue(msg);
await Task.Delay(50); // To prevent a tight loop within a Task thread we should sleep here.
return(false);
}
if (await Data.MtaTransaction.HasBeenHandledAsync(msg.ID))
{
msg.IsHandled = true;
return(true);
}
// Get the send that this message belongs to so that we can check the send state.
Send snd = await SendManager.Instance.GetSendAsync(msg.InternalSendID);
switch (snd.SendStatus)
{
// The send is being discarded so we should discard the message.
case SendStatus.Discard:
await MtaMessageHelper.HandleMessageDiscardAsync(msg);
return(false);
// The send is paused, the handle pause state will delay, without deferring, the message for a while so we can move on to other messages.
case SendStatus.Paused:
await MtaMessageHelper.HandleSendPaused(msg);
return(false);
// Send is active so we don't need to do anything.
case SendStatus.Active:
break;
// Unknown send state, requeue the message and log error. Cannot send!
default:
msg.AttemptSendAfterUtc = DateTime.UtcNow.AddMinutes(1);
await RabbitMqOutboundQueueManager.Enqueue(msg);
Logging.Error("Failed to send message. Unknown SendStatus[" + snd.SendStatus + "]!");
return(false);
}
bool result;
// Check the message hasn't timed out. If it has don't attempt to send it.
// Need to do this here as there may be a massive backlog on the server
// causing messages to be waiting for ages after there AttemptSendAfter
// before picking up. The MAX_TIME_IN_QUEUE should always be enforced.
if (msg.AttemptSendAfterUtc - msg.QueuedTimestampUtc > new TimeSpan(0, MtaParameters.MtaMaxTimeInQueue, 0))
{
await MtaMessageHelper.HandleDeliveryFailAsync(msg, MtaParameters.TIMED_OUT_IN_QUEUE_MESSAGE, null, null);
result = false;
}
else
{
MailAddress mailAddress = new MailAddress(msg.RcptTo[0]);
MailAddress mailFrom = new MailAddress(msg.MailFrom);
MXRecord[] mXRecords = DNSManager.GetMXRecords(mailAddress.Host);
// If mxs is null then there are no MX records.
if (mXRecords == null || mXRecords.Length < 1)
{
await MtaMessageHelper.HandleDeliveryFailAsync(msg, "550 Domain Not Found.", null, null);
result = false;
}
else if (IsMxBlacklisted(mXRecords))
{
await MtaMessageHelper.HandleDeliveryFailAsync(msg, "550 Domain blacklisted.", null, mXRecords[0]);
result = false;
}
else
{
// The IP group that will be used to send the queued message.
VirtualMtaGroup virtualMtaGroup = VirtualMtaManager.GetVirtualMtaGroup(msg.VirtualMTAGroupID);
VirtualMTA sndIpAddress = virtualMtaGroup.GetVirtualMtasForSending(mXRecords[0]);
SmtpOutboundClientDequeueResponse dequeueResponse = await SmtpClientPool.Instance.DequeueAsync(sndIpAddress, mXRecords);
switch (dequeueResponse.DequeueResult)
{
case SmtpOutboundClientDequeueAsyncResult.Success:
case SmtpOutboundClientDequeueAsyncResult.NoMxRecords:
case SmtpOutboundClientDequeueAsyncResult.FailedToAddToSmtpClientQueue:
case SmtpOutboundClientDequeueAsyncResult.Unknown:
break; // Don't need to do anything for these results.
case SmtpOutboundClientDequeueAsyncResult.FailedToConnect:
await MtaMessageHelper.HandleFailedToConnectAsync(msg, sndIpAddress, mXRecords[0]);
break;
case SmtpOutboundClientDequeueAsyncResult.ServiceUnavalible:
await MtaMessageHelper.HandleServiceUnavailableAsync(msg, sndIpAddress);
break;
case SmtpOutboundClientDequeueAsyncResult.Throttled:
await MtaMessageHelper.HandleDeliveryThrottleAsync(msg, sndIpAddress, mXRecords[0]);
break;
case SmtpOutboundClientDequeueAsyncResult.FailedMaxConnections:
msg.AttemptSendAfterUtc = DateTime.UtcNow.AddSeconds(2);
await RabbitMqOutboundQueueManager.Enqueue(msg);
break;
}
SmtpOutboundClient smtpClient = dequeueResponse.SmtpOutboundClient;
// If no client was dequeued then we can't currently send.
// This is most likely a max connection issue. Return false but don't
// log any deferal or throttle.
if (smtpClient == null)
{
result = false;
}
else
{
try
{
Action <string> failedCallback = delegate(string smtpResponse)
{
// If smtpRespose starts with 5 then perm error should cause fail
if (smtpResponse.StartsWith("5"))
{
MtaMessageHelper.HandleDeliveryFailAsync(msg, smtpResponse, sndIpAddress, smtpClient.MXRecord).Wait();
}
else
{
// If the MX is actively denying use service access, SMTP code 421 then we should inform
// the ServiceNotAvailableManager manager so it limits our attepts to this MX to 1/minute.
if (smtpResponse.StartsWith("421"))
{
ServiceNotAvailableManager.Add(smtpClient.SmtpStream.LocalAddress.ToString(), smtpClient.MXRecord.Host, DateTime.UtcNow);
MtaMessageHelper.HandleDeliveryDeferral(msg, smtpResponse, sndIpAddress, smtpClient.MXRecord, true);
}
else
{
// Otherwise message is deferred
MtaMessageHelper.HandleDeliveryDeferral(msg, smtpResponse, sndIpAddress, smtpClient.MXRecord, false);
}
}
throw new SmtpTransactionFailedException();
};
// Run each SMTP command after the last.
await smtpClient.ExecHeloOrRsetAsync(failedCallback);
await smtpClient.ExecMailFromAsync(mailFrom, failedCallback);
await smtpClient.ExecRcptToAsync(mailAddress, failedCallback);
await smtpClient.ExecDataAsync(msg.Message, failedCallback, async (response) => {
await MtaMessageHelper.HandleDeliverySuccessAsync(msg, sndIpAddress, smtpClient.MXRecord, response);
});
SmtpClientPool.Instance.Enqueue(smtpClient);
result = true;
}
catch (SmtpTransactionFailedException)
{
// Exception is thrown to exit transaction, logging of deferrals/failers already handled.
result = false;
}
catch (Exception ex)
{
Logging.Error("MessageSender error.", ex);
if (msg != null)
{
MtaMessageHelper.HandleDeliveryDeferral(msg, "Connection was established but ended abruptly.", sndIpAddress, smtpClient.MXRecord, false);
}
result = false;
}
finally
{
if (smtpClient != null)
{
smtpClient.IsActive = false;
smtpClient.LastActive = DateTime.UtcNow;
}
}
}
}
}
return(result);
}