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mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

Hi, 

Our sending SMTP server is no longer able to send e-mails through to @ntlworld.com domains.

We are receiving the following rejection message:

 

connect to mx.tb.ukmail.iss.as9143.net[208.91.112.55]:25: Connection timed out

the sending domain is @hugheseurope.com and the sending STMP server is mail.hugheseurope.com and we are not RBL blacklisted.

External email attempts work correctly from eg a hotmail.com account.

Please could you advise as this is causing important communication issues. 

Many Thanks.  

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

The first thing that I would do is have a proper look at the error message. 

This looks to be your server not being able to reach Virgin Media's.  The reason I say this is because your server is reporting connection timed out. 

Have you tried tracing a route to the host?

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

Thank you for your response. The SMTP server can reach mx3.tb.ukmail.iss.as9143.net, it responds to pings as shown below.  

PING mx3.tb.ukmail.iss.as9143.net (208.91.112.55) 56(84) bytes of data.
64 bytes from 208.91.112.55: icmp_seq=1 ttl=50 time=151 ms
64 bytes from 208.91.112.55: icmp_seq=2 ttl=50 time=150 ms
64 bytes from 208.91.112.55: icmp_seq=3 ttl=50 time=150 ms
64 bytes from 208.91.112.55: icmp_seq=4 ttl=50 time=151 ms  

If I try to telnet to the address on port 25, 465 or 587, all connections fail. 

Also if I use a the mxtoolbox test against the address it also fails to connect?

https://mxtoolbox.com/diagnostic.aspx

Thanks. 

 

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

Please don't use mx3

The MX server names that your server connects to are publicly available using a DNS lookup

 

C:\Users\timdu>dig mx virginmedia.com

; <<>> DiG 9.10.6-P1 <<>> mx virginmedia.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 54827
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;virginmedia.com.               IN      MX

;; ANSWER SECTION:
virginmedia.com.        15634   IN      MX      1 mx.tb.ukmail.iss.as9143.net.
virginmedia.com.        15634   IN      MX      1 mx.mnd.ukmail.iss.as9143.net.

;; Query time: 21 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Dec 11 09:27:53 GMT Standard Time 2018
;; MSG SIZE  rcvd: 110

There are multiple Mail servers connected to  each of these MX addresses but the connection is made to one of these two hostnames

 

Your error message clearly states the hostname that your mail server was trying to connect to:

mx.tb.ukmail.iss.as9143.net[208.91.112.55]:25: Connection timed out

Here's what I get when I try that server:

telnet mx.tb.ukmail.iss.as9143.net 25

220 mx7.tb.ukmail.iss.as9143.net mx7.tb.ukmail.iss.as9143.net ESMTP server ready
ehlo desktop
250-mx7.tb.ukmail.iss.as9143.net hello [80.195.xxx.xxx], pleased to meet you
250-HELP
250-SIZE 30000000
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-STARTTLS
250 OK
quit
221 2.0.0 mx7.tb.ukmail.iss.as9143.net mx7.tb.ukmail.iss.as9143.net closing connection

BTW here's what happens when I try to connect to mx7 directly.

C:\Users\timdu>telnet mx7.tb.ukmail.iss.as9143.net 25
Connecting To mx7.tb.ukmail.iss.as9143.net...Could not open connection to the host, on port 25: Connect failed

This is by design.  Because the server sits behind the Mail Exchanger gateway it's firewalled so that only connections that come from via the gateway are allowed.

BTW - A slight criticism, why on earth would you try to connect to a mail exchanger on anything other than port 25?

587 and 465 are used at the start of the SMTP chain for email submission, but mail exchangers exclusively listen on port 25

Tim

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

Thank you again for assisting.

After a bit further investigation it seems as if it's DNS related. 

an NSLOOKUP of mx.tb.ukmail.iss.as9143.net returns 

208.91.112.55

I cannot connect on port 25 to this address.

An NSLOOKUP with google's public DNS servers also serves 208.91.112.55.

If I check however https://www.whatsmydns.net/#A/mx.tb.ukmail.iss.as9143.net

It shows a different address, 212.54.56.11, which I can connect to on port 25.

Which IP address do you see and which DNS server are you using if public?  

Thanks.

 

 

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

That's odd - because I'm using Google's public DNS here

C:\Users\timdu>dig mx.tb.ukmail.iss.as9143.net

; <<>> DiG 9.10.6-P1 <<>> mx.tb.ukmail.iss.as9143.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53711
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;mx.tb.ukmail.iss.as9143.net.   IN      A

;; ANSWER SECTION:
mx.tb.ukmail.iss.as9143.net. 2442 IN    A       212.54.56.11

;; Query time: 18 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Dec 11 11:06:00 GMT Standard Time 2018
;; MSG SIZE  rcvd: 72

And if I use Cloudmarks as well.

C:\Users\timdu>dig mx.tb.ukmail.iss.as9143.net @1.1.1.1

; <<>> DiG 9.10.6-P1 <<>> mx.tb.ukmail.iss.as9143.net @1.1.1.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25684
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1452
;; QUESTION SECTION:
;mx.tb.ukmail.iss.as9143.net.   IN      A

;; ANSWER SECTION:
mx.tb.ukmail.iss.as9143.net. 2918 IN    A       212.54.56.11

;; Query time: 19 msec
;; SERVER: 1.1.1.1#53(1.1.1.1)
;; WHEN: Tue Dec 11 11:08:51 GMT Standard Time 2018
;; MSG SIZE  rcvd: 72

I'm not a Virgin Media employee myself, but I am quite clued up on their email setup.

Since taking the Email back "in house" in 2015, the email service has been hosted by Ziggo Internet (another company in the Liberty Global group) in Utrecht.

Those servers have NEVER been on 208.91.112.55 - Which is run by the ISP Fortinet based in Canada

I'm going to ask that @Jen_A  (who works for Virgin Media) to take a look at this, however my thoughts are that you ask your IT department to look at why your DNS is giving the wrong results.  (I'd look at etc/hosts on the affected system as well as trying to clear the DNS cache)

Tim

Edit based on what I'm seeing here, this isn't down to Virgin Media, but looks to be an issue on your systems.

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

Indeed it isn't... I realised that our firewall was blocking the DNS responses and categorising them as "phishing" and providing us with the 208.91.112.55 re-directed address.

We have had to whitelist the server and all is well again, thank you again for your help.

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Re: mx3.tb.ukmail.iss.as9143.net rejecting emails from company domain

As you've found the solution you might want to mark your last post as the helpful answer then.

Glad you've gotten to the bottom of it.

Tim

P.S.  This is why DNS redirection is bad.

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