False "Message Delivery Failure "

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TheDaywalker
Posts: 7
Joined: Tue May 06, 2014 8:23 am

False "Message Delivery Failure "

Post by TheDaywalker »

Hello,
on a specific domain, we are getting mail delivery failures.
When I inspected the issue, I found this:

-----Original Message-----
From: Delivery Subsystem <POSTMASTER@***.com>
Sent: Thursday, August 12, 2021 12:25 AM
To: umitakyuz@***.com
Subject: Message Delivery Failure - EFT/SWIFT Hesap Ekleme


MailEnable: Message could not be delivered to some recipients.
The following recipient(s) could not be reached:

Recipient: [SMTP:****@takasbank.com.tr]
Reason: Mail server for takasbank.com.tr is not contactable. Message
has expired and has been returned to Sender.




Message contents follow:

Received: from MUHASEBE1 ([78.189.216.***]) by ***.com with
MailEnable ESMTPA; Mon, 9 Aug 2021 15:43:40 +0300
From: =?iso-8859-9?B?3G1pdCBBa3n8eg==?= <umitakyuz@***.com>
To: <***@takasbank.com.tr>
Subject: EFT/SWIFT Hesap Ekleme
Date: Mon, 9 Aug 2021 15:43:37 +0300
Message-ID: <003601d78d1c$2d179580$8746c080$@hakandoviz.com>
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary="----=_NextPart_000_0037_01D78D35.526569C0"
X-Mailer: Microsoft Outlook 16.0
Thread-Index: AdeNHCf0WU0VYvN4Tqa+S/Awbzr4rQ==
Content-Language: tr
X-ME-Bayesian: 40.000000

This is a multipart message in MIME format.

------=_NextPart_000_0037_01D78D35.526569C0
Content-Type: multipart/related;
boundary="----=_NextPart_001_0038_01D78D35.526569C0"


------=_NextPart_001_0038_01D78D35.526569C0
Content-Type: multipart/alternative;
boundary="----=_NextPart_002_0039_01D78D35.526569C0"


------=_NextPart_002_0039_01D78D35.526569C0
Content-Type: text/plain;
charset="iso-8859-9"
Content-Transfer-Encoding: quoted-printable

As you can see, it says "the remote mail server is not contactable."
I log on to the server and check the connection for the remote mailserver by telnet.
Yes, the port 587 was unreachable but port 25 was running OK on the remote side and the connection succedeed.

Doesn't MailEnable ever use port 25 for outgoing smpt servers? Or is there a configuration area for this that I'm missing?

MailEnable-Ian
Site Admin
Posts: 9738
Joined: Mon Mar 22, 2004 4:44 am
Location: Melbourne, Victoria, Australia

Re: False "Message Delivery Failure "

Post by MailEnable-Ian »

Hi,

MailEnable will always send over port 25. This is the mail server sending port standard for all mail servers. You need to inspect the SMTP log files in more detail to see if there are any error occurring when trying to send the message to the remote mail server.
Regards,

Ian Margarone
MailEnable Support

TheDaywalker
Posts: 7
Joined: Tue May 06, 2014 8:23 am

Re: False "Message Delivery Failure "

Post by TheDaywalker »

I've checked the log file, here it is:
08/09/21 15:43:40 ME-I0108: [1560] Relay Granted: Sender has authenticated.
08/09/21 15:43:42 ME-I0149: [1560] 840345D5847246CA8782F9CDD200EF56.MAI was received successfully and delivery thread was initiated
08/09/21 15:43:43 ME-I0018: [4B28246F2DA94A8992EE9086AD40FAA2.MAI] Outbound message from ([SMTP:****@hakandoviz.com]) requeued as [EE88D31531A84FF0B831E3423D2D8887.MAI] to the target domain [takasbank.com.tr]
08/09/21 15:43:43 ME-I0123: Domain [takasbank.com.tr] has MX list [mail1.takasbank.com.tr,mail2.takasbank.com.tr,mail3.takasbank.com.tr,mail4.takasbank.com.tr]
08/09/21 15:43:43 ME-I0026: [EE88D31531A84FF0B831E3423D2D8887.MAI] Sending message
08/09/21 15:43:44 ME-I0074: [1560] (Debug) End of conversation
08/09/21 15:43:50 MF-E0039: [EE88D31531A84FF0B831E3423D2D8887.MAI] DNS Lookup failure (11002): Could not resolve domain mail1.takasbank.com.tr to IP address.
08/09/21 15:43:50 ME-I1350: [EE88D31531A84FF0B831E3423D2D8887.MAI] Attempting to connect to MX 2 of 4 (mail2.takasbank.com.tr).
08/09/21 15:44:00 MF-E0039: [EE88D31531A84FF0B831E3423D2D8887.MAI] DNS Lookup failure (11002): Could not resolve domain mail2.takasbank.com.tr to IP address.
08/09/21 15:44:00 ME-I1350: [EE88D31531A84FF0B831E3423D2D8887.MAI] Attempting to connect to MX 3 of 4 (mail3.takasbank.com.tr).
08/09/21 15:44:04 MF-E0039: [EE88D31531A84FF0B831E3423D2D8887.MAI] DNS Lookup failure (11002): Could not resolve domain mail3.takasbank.com.tr to IP address.
08/09/21 15:44:04 ME-I1350: [EE88D31531A84FF0B831E3423D2D8887.MAI] Attempting to connect to MX 4 of 4 (mail4.takasbank.com.tr).
08/09/21 15:44:06 MF-E0039: [EE88D31531A84FF0B831E3423D2D8887.MAI] DNS Lookup failure (11002): Could not resolve domain mail4.takasbank.com.tr to IP address.
08/09/21 15:44:06 ME-E0059: [EE88D31531A84FF0B831E3423D2D8887.MAI] Message Delivery Failure. Attempt (0): Could not connect to mail server for domain (takasbank.com.tr). The remote mail server could not be contacted at this time. Message has been requeued.
So, the mailenable server complains about the DNS record not resolving. Okay.
On the server machine using the default nslookup command, the DNS lookup fails. I guess this is about extra protection for the remote mailserver because it is a local business and they probably blocked the DNS server from foreign (other countries) IP address.
C:\Users\Administrator>nslookup mail1.takasbank.com.tr
Server: ns1-coloc.hetzner.de
Address: 213.133.98.98

*** ns1-coloc.hetzner.de can't find mail1.takasbank.com.tr: Server failed

C:\Users\Administrator>nslookup mail1.takasbank.com.tr 8.8.8.8
Server: dns.google
Address: 8.8.8.8

Non-authoritative answer:
Name: mail1.takasbank.com.tr
Address: 185.96.112.12
But, as you can see above, using Google dns (8.8.8.8) it resolves quite fine and I've already put the 8.8.8.8 at the FIRST in the SMTP Properties window DNS addresses section.
So, if MailEnable will NOT use those DNS, why it asks for it at first place? WHY? WHYYYYYYYYYYYYY??????????????

Okay, I'm REALLY getting frustrated more and more each day by this stupid mailserver...

mikebonte
Posts: 49
Joined: Wed Nov 30, 2011 6:04 pm
Location: New Jersey

Re: False "Message Delivery Failure "

Post by mikebonte »

I've been using MailEnable for decades and I've never been 100% certain why the SMTP connector has a DNS settings option other than for a failover situation. I don't know if ME uses it's own DNS settings first, then the OS or vice-versa.

Regardless, I keep them set the same for both the SMTP connector as well as the NIC in the server. In my case, I am running a local DNS server on the same box so everything is set to the local address and then the DNS server is using root lookups.

There is something to keep in mind about DNS failover... some DNS servers will return a garbage value instead of NXDOMAIN on a resolution failure. That would prevent the rollover of the DNS lookup to the next server in the list. I have run into this problem with home user VPNS with certain ISPs that return their own site on a DNS lookup failure as a well to "be helpful" and provide a friendly webpage to the user. I'm not saying this is specifically happening in your situation, but there may be something along these lines that are preventing ME or the OS from advancing to the next DNS server. Traditional troubleshooting like NSLOOKUP will not necessarily uncover this.

MailEnable has been a pretty robust solution for us. It's not perfect, but don't knock it because you are having DNS issues.

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