SMTP Problem... No apparent error

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kewlkeed
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SMTP Problem... No apparent error

Post by kewlkeed » 2007-04-16 15:09

"SMTPC" 2060 1036 "2007-04-15 04:28:01.124" "207.253.83.251" "RECEIVED: 250 2.1.0 <######@#####.ca>... Sender ok"
"DEBUG" 2060 "2007-04-15 04:28:01.124" "SMTPClientConnection::~_ParseASCII() - 6"
"SMTPC" 2060 1036 "2007-04-15 04:28:01.124" "207.253.83.251" "SENT: RCPT TO:<######@######.com>"
"DEBUG" 2060 "2007-04-15 04:28:01.184" "SMTPClientConnection::_ParseASCII()"
"SMTPC" 2060 1036 "2007-04-15 04:28:01.184" "207.253.83.251" "RECEIVED: 250 2.1.5 <####@####.com>... Recipient ok"
"SMTPC" 2060 1036 "2007-04-15 04:28:01.184" "207.253.83.251" "SENT: DATA"
"DEBUG" 2060 "2007-04-15 04:28:01.184" "SMTPClientConnection::~_ParseASCII() - 7"
"DEBUG" 2060 "2007-04-15 04:28:01.234" "SMTPClientConnection::_ParseASCII()"
"SMTPC" 2060 1036 "2007-04-15 04:28:01.234" "207.253.83.251" "RECEIVED: 354 Enter mail, end with "." on a line by itself"
"DEBUG" 2060 "2007-04-15 04:28:01.234" "SocketConnection::SendFileContents()"
"DEBUG" 2060 "2007-04-15 04:28:01.234" "TransparentTransmissionBuffer::Initialize()"
"DEBUG" 2060 "2007-04-15 04:28:01.234" "SocketConnection::SendFileContents() - E2"
"SMTPC" 2060 1036 "2007-04-15 04:28:01.234" "207.253.83.251" "SENT: [nl]."
"DEBUG" 2060 "2007-04-15 04:28:01.234" "SMTPClientConnection::~_ParseASCII() - 8"
"DEBUG" 1368 "2007-04-15 04:28:07.523" "GreyListCleanerTask::DoWork()"
"TCPIP" 2060 "2007-04-15 04:28:23.326" "Disconnecting socket 1612 for session 1035"
"DEBUG" 2060 "2007-04-15 04:28:23.326" "Socket::~Socket(ID: 1035)"
"DEBUG" 3372 "2007-04-15 04:28:23.326" "SD::~_InitiateExternalConnection-5"
"DEBUG" 3372 "2007-04-15 04:28:23.326" "SD::~_DeliverToExternalAccounts-2"
"DEBUG" 3372 "2007-04-15 04:28:23.326" "SD::_CollectDeliveryResult"
"DEBUG" 3372 "2007-04-15 04:28:23.326" "SD::~_CollectDeliveryResult"
"DEBUG" 3372 "2007-04-15 04:28:23.326" "SD::_RescheduleDelivery"
"APPLICATION" 3372 "2007-04-15 04:28:23.326" "SMTPDeliverer - Message 33290: Message could not be delivered. Scheduling it for later delivery."




(Email addresses were deliberately changed)

What is going on here? It looks like the server recieving the email is simply dropping the connection or not seeing the email being sent to it?

kewlkeed
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Post by kewlkeed » 2007-04-16 16:20

This problem seems to be happening more and more often,

There are no other links or reasons between the different occurances other than the fact that email to thoes certain addresses NEVER work. It's not a case where one day it will, and the next day it won't. The server is on the latest stable release and the problem was happening both now and before the server was upgraded about 2 weeks ago. The server normally handles aprox 100-200 emails per hour and it only seems that 2-3 of these emails are having this problem. As luck would have it they are important emails however so the problem needs to be resolved. The companies that are supposed to recieve these emails all have properly formatted DNS/MX and are rather large companies so I don't believe the problem is on their end. The hmailserver has been in operation for over a year now and nothing has been changed in its setup/firewall/etc.

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martin
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Post by martin » 2007-04-16 19:37

As you say, it looks like the remote server disconnects hMailServer after a while. Really hard to say why it does this. If you are using any router or "live" virus scanner which scans SMTP traffic, that would be the first thing to check.

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Post by kewlkeed » 2007-04-16 23:23

Could it be that the recieving end's server is simply waiting an extended time before it replies back to mine? (Peraps some obscure anti-spam method?) and my connection is simply timing out? If so how would I go about increasing the timeout setting?

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Post by minsik » 2007-04-17 06:48

be aware how assp and others work, delaying, greylisting etc.

my basic understanding, is that at first a new email from mr x will have the send ip rx ip and who its from and to recorded in a tuplet. Then the email is 471 or is it 571, replied that there is a delay (not wont accept) then after the wait time of the send email server the message tries again. if there is not enought wait time (as set by the rx email program then another cant accpet now but try again later command is sent back. the details are checked against the original and if match then keep the info. Next time the send email server tries there should have passed the wait time. set for 5-15 minutes usually, then the send email server tries again, recieve email program says, ok wait time is passed, you are same i[p and other details you must be genuine sender i will recieve the email, then it will be compared to blacklisting, blocked ip etc and then recieve for the person it was originally destined for. We find the delaying adds a huge spam prevention and most (but not all) email servers can cope with this all ok. After its accepted then that tuplet is stored for 14 days as a valid combination and new emails from that ip for that person will be accepted without delay. Everyso often the progrma will clear out old then xxx days listings and so it repeatd again.

Hope this might be some help.

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Post by kewlkeed » 2007-04-17 15:05

I will try changing the delay between resends to be aprox 10minutes. Does this sound like a good time?

Also is there a way to increase the timeout setting for the TCP connection? Or should I worry about that at this time?

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Post by kewlkeed » 2007-04-17 20:23

Tried the delay at 5 - 10 - 15 minute intervals and ran tests... Still no dice. Problem is still there.

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martin
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Post by martin » 2007-04-17 21:18

In this case, the connection is closed after about 22 seconds. The SMTP timeout in hMailServer is >10 minutes, so that can't be the problem.

What about virus scanners and such things? Are you running any "live" virus scanners on the server which scans email traffic? Or any bandwidth limiters or similar?

You could perhaps use http://www.ethereal.com/ to log the SMTP traffic and then see who is actually closing the connection. Unless you know a bit about TCP/IP that may be too complicated though. If you manage to create a log using the tool, you can zip and send it to me at martin@hmailserver.com and I can have a look at it.

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Post by kewlkeed » 2007-04-19 16:05

No live virus scanner (Yes I know bad idea, but just want to establish testing first)

I will do a packet capture and see what the results are.

Thanks!

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