| SMTP Greeting from remote host [message #121438] |
Wed, 20 May 2015 23:16  |
Maurice Herbst
Messages: 5
Registered: July 2012
Location: Reno, NV
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A Customer of ours just changed ISP's and now we cant send them email the error we receive is:
Action: delayed
Status: 4.4.2
Remote-MTA: mail.PRECISIONMETALS.COM
Diagnostic-Code: SMTP; No greeting from remote host
The email eventually fails.
When I test this from a command line on our server I get the following:
telnet mail.precisionmetals.com 25
Trying 162.210.109.180...
Connected to mail.precisionmetals.com.
Escape character is '^]'.
No banner is ever sent however if I manually type the ehlo command I get the banner.
When I test this from Putty I get a banner response as seen below without typing the ehlo command:
220 Tin.PRECISIONMETALS.LOCAL Microsoft ESMTP MAIL Service ready at Wed, 20 May 2015 14:10:14 -0700
I can send to their server through GMAIL or Hotmail, and they can send to us with no issues.
They are running Exchange 2010 and we are running Kerio Connect 8.2.4
We have been seeing a few small issues with sending however most emails are received by our recipients with no issue. This server has been fully functional for over 3 years without any functional problems.
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| Re: SMTP Greeting from remote host [message #121440 is a reply to message #121439] |
Thu, 21 May 2015 00:01  |
Maurice Herbst
Messages: 5
Registered: July 2012
Location: Reno, NV
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First its not precisionmetals.com its mail.precisionmetals.com I have ran this tool for them before on the mail.precisionmetals.com and only saw the PTR issue. Would you be so kind as to run it again and see what you get.
Thank you
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| Re: SMTP Greeting from remote host [message #121443 is a reply to message #121440] |
Thu, 21 May 2015 00:11 |
ksnyder
Messages: 557
Registered: August 2014
Location: USA
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Maurice,
Please click the link I provided in the top of the post. As you can see throughout my response, the tool (mxtoolbox) ran against mail.precisionmetals.com. We're not very motivated to help people solve their MS Exchange problems as you can probably imagine. Perhaps I'm missing something from the wording of your post and you're concerned that this is a problem with your mail server? Can you confirm?
Regards,
Ken Snyder
Ken Snyder
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| Re: SMTP Greeting from remote host [message #121444 is a reply to message #121443] |
Thu, 21 May 2015 00:25 |
Maurice Herbst
Messages: 5
Registered: July 2012
Location: Reno, NV
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ksnyder - I clicked the link the only issue I see is the PTR issue:Reverse DNS Resolution - No PTR Record
I wouldn't think that would keep me from getting the SMTP banner from a command line on a Linux server.
Believe me when I say I don't want to help anyone with MS Exchange either hence the reason I run Kerio 
Yes I am concerned that it is our server, plus they are a valued customer and I am trying to be understanding for that reason.
What concerns me is that from Putty I get the banner just fine but when running telnet from a command line on the server I do not.
IF you at Kerio can tell me 100% that my server is not the issue I will be happy to close it and move on.
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| Re: SMTP Greeting from remote host [message #121446 is a reply to message #121445] |
Thu, 21 May 2015 00:46 |
Maurice Herbst
Messages: 5
Registered: July 2012
Location: Reno, NV
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Ah found it I will turn it on and see what I get.
Here is the debug logs I get:
[20/May/2015 15:48:34][19136] {smtpc} Sending email to SMTP server mail.PRECISIONMETALS.COM, delivering mail from <mherbst<_at_>eetechinc.com>
[20/May/2015 15:48:34][19136] {smtpc} Connecting to 162.210.109.180 (mail.PRECISIONMETALS.COM) using local interface 0.0.0.0...
[20/May/2015 15:48:34][19136] {smtpc} Connected to mail.PRECISIONMETALS.COM
[20/May/2015 15:53:34][19136] {smtpc} SMTP connection closed while reading SMTP reply
[20/May/2015 15:53:34][19136] {smtpc} No greeting from server mail.PRECISIONMETALS.COM
[Updated on: Thu, 21 May 2015 00:55] Report message to a moderator |
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| Re: SMTP Greeting from remote host [message #123450 is a reply to message #121438] |
Tue, 11 August 2015 22:23 |
vincent.iveze
Messages: 5
Registered: August 2015
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My server has exactly the same problem with Microsoft mail servers only (outlook.com, hotmail.com, etc...). If i connect with telnet to them, they hang before the greeting. To get a greeting i do not need to send a full HELO. If i put in an enter right after the line "Escape char...." appears, it works too. Other mail servers give me back the greeting without doing anything.
My conclusion is that Microsoft mail servers need the client to send something first, even if it is just an enter. Is there in Kerio-Connect some option to say: Send an enter right after the tcp handshake?
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| Re: SMTP Greeting from remote host [message #123459 is a reply to message #123450] |
Wed, 12 August 2015 09:34 |
clan
Messages: 187
Registered: May 2011
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vincent.iveze wrote on Tue, 11 August 2015 22:23My conclusion is that Microsoft mail servers need the client to send something first, even if it is just an enter. Is there in Kerio-Connect some option to say: Send an enter right after the tcp handshake?
I think you are wrong, I just tried connecting with telnet to some of the hotmail mail servers and got the greeting immediately.
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| Re: SMTP Greeting from remote host [message #123502 is a reply to message #123459] |
Wed, 12 August 2015 22:41 |
vincent.iveze
Messages: 5
Registered: August 2015
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I have checked tcpdump and the tcp 3-way handshake happens (syn syn-ack ack). Then nothing (waiting for greeting) when connecting a Microsoft mail server. So what telnet sends (CRLF) is irrelevant. It should and does not send anything.
We did recently migrate from os-x to Centos 7. Tested telnet on different os-es and found that os-x and windows tcp give microsoft mail servers what they want from within our internal network. None of the Centos do (6 or 7).
There are some possibilities on our network:
1) Centos tcp does not work with Microsoft tcp
2) Bad gateway which mysteriously only affects Centos
In both cases it is still weird that the issue is only with Microsoft mail servers.
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| Re: SMTP Greeting from remote host [message #123518 is a reply to message #123502] |
Thu, 13 August 2015 14:57 |
clan
Messages: 187
Registered: May 2011
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I think it is save to say, that you can rule out 1), I would expect many more complaints if that was the case.
2) could actually be (almost) the case, just not for Centos, but the IP address you assigned to the server. This is still a long shot, but is the IP of the Centos servers blocked somewhere? Or routed differently?
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| Re: SMTP Greeting from remote host [message #123570 is a reply to message #123518] |
Sat, 15 August 2015 01:27 |
vincent.iveze
Messages: 5
Registered: August 2015
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Just back from testing with a Linux firewall/nat gateway, and it works. This is important information for anyone who has specifically Kerio on a Linux server and this problem with Microsoft mail servers (hotmail.com, outlook.com, etc....). They should check their firewall/nat gateway for any mail protection settings, and if that does not work test with another gateway or better a Linux gateway.
My best guess is that an older firewall/nat gateway malforms modern Linux tcp packets slightly. Not enough to make any mail server angry, except those of Microsoft. Probably a misplaced action of them in an attempt to avoid spam.
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