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JHam
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Emails from specific address being bounced back

My husband is suddenly no longer able to email my son’s VM address. The emails are being bounced back as undeliverable, yet he can send them to me (At my gmail address) and I can then send on to my son. My son is also not getting email from his university while other classmates are, and we are wondering if these are being blocked for some reason. No changes have been made at our end. Any thoughts as to why this would suddenly happen? Thanks. 

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MissPasko
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Re: Emails from specific address being bounced back

Please post the undeliverable message your husband receives, but anonymise it by deleting or xx-ing out the parts in front of the @domain.com of ALL email addresses.

There are often clues in the message.

For the university emails, have your son check his webmail settings to rule out any filter/blacklist/autoforward rules that mean he doesn't see them.  Also check the spam FOLDER on webmail.  Then he would have to go to the sender to start the investigation.  VM would get involved if the sender tells him that they are being received at the VM end.  They would be able to supply authentication logs for this, then VM can search out why they aren't reaching your son's mailbox.  That is my layman's understanding.


~ ~ ~ ~ ~ ~ ~ ~ *\o/* ~ ~ ~ ~ ~ ~ ~ *\o/* ~ ~ ~ ~ ~ ~ ~ ~ *\o/* ~ ~ ~ ~ ~ ~ ~ *\o/* ~ ~ ~ ~ ~ ~ ~ ~

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JHam
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Re: Emails from specific address being bounced back

Hi,

Thanks for your reply. I have the details of the undeliverable message below. We have checked autoforward, blacklist, spam etc and nothing is set up. We are waiting to hear back from the uni. 
does this give any clues?

Delivery has failed to these recipients or groups:

r************n@virginmedia.com

 

A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

The following organization rejected your message: mx.tb.ukmail.iss.as9143.net.

 

Diagnostic information for administrators:

Generating server: smtp2.XXXXXXXXX.com

r************n@virginmedia.com

mx.tb.ukmail.iss.as9143.net #<mx.tb.ukmail.iss.as9143.net #4.0.0 smtp; 421 EHLO MXIN201 Your HELO/EHLO smtp2.XXXXXXX.com is not matching your DNS configuration mail.XXXXXXX.com,mail.XXXXXXX.co.uk ;id=eKlWjiiv0ohd5;sid=eKlWjiiv0ohd5;mta=mx9.tb;d=20200528;t=174818[CET];ipsrc=192.149.117.122;> #SMTP#

Original message headers:

Return-Path: <prvs=14156f60d8=XXXXXXXXXX@XXXXXXX.com>

Received: from smtp2.local (localhost [127.0.0.1]) by smtp2.XXXXXXX.com

(MTA) with ESMTP id 49Wc8p53LHz3dkQP for <r************n@virginmedia.com>;

Tue, 26 May 2020 15:41:14 +0100 (BST)

From: XXXXXXXXX <XXXXXXXX@XXXXXX.com>

To: XXXXXXXX<r************n@virginmedia.com>

Subject: RE: [EXTERNAL] Excel stats

Thread-Topic: [EXTERNAL] Excel stats

Thread-Index: AQHWM2k1ItXc6dFksUqrjNl5/AOws6i6cCTw

Date: Tue, 26 May 2020 14:39:56 +0000

Message-ID: <7DFA17C32159F14BB05FEBAC86B211399028A77F@EKIPRDEXM01.core.local>

References: <6C0DB2B6-E453-4716-A4CA-C060A8B11CC5@virginmedia.com>

In-Reply-To: <6C0DB2B6-E453-4716-A4CA-C060A8B11CC5@virginmedia.com>

Accept-Language: en-GB, en-US

Content-Language: en-US

X-MS-Has-Attach: yes

X-MS-TNEF-Correlator:

x-originating-ip: [10.132.204.30]

Content-Type: multipart/mixed;

boundary="_002_7DFA17C32159F14BB05FEBAC86B211399028A77FEKIPRDEXM01core_"

MIME-Version: 1.0

x-msw-jemd-newsletter: false

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ravenstar68
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Re: Emails from specific address being bounced back

I can't speak for the University emails, but the mail server trying to deliver mail to you isn't set up properly.

Consider my own mail server box.timothydutton.co.uk

When I send mail to any email address it advertises itself using it's FQDN.  Virgin Media then looks up the address of the FQDN

dig a box.timothydutton.co.uk +short
77.68.89.100

Now a properly configured mail server should be set up so that doing a reverse DNS lookup gives us the orginal hostname

dig -x 77.68.89.100 +short
box.timothydutton.co.uk.

Mail administrators may elect to reject mail from sources that don't conform to this standard in an attempt to cut down on Spam

So lets look at the IP address - 192.149.117.122

dig -x 192.149.117.122 +short
mail.british-energy.co.uk.
mail.british-energy.com.

Reverse DNS MUST only resolve to a single hostname (unlike forward DNS where a single hostname MAY resolve to multiple IP addresses) - So straight away we have a problem.

From the bounce message the server actually identifies itself with a different FQDN - smtp2.edf-energy.com

Finally if we look at the hostname smtp2.edf-energy.com

dig a smtp2.edf-energy.com @1.1.1.1

; <<>> DiG 9.11.3-1ubuntu1.12-Ubuntu <<>> a smtp2.edf-energy.com @1.1.1.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 21165
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1452
;; QUESTION SECTION:
;smtp2.edf-energy.com. IN A

;; AUTHORITY SECTION:
edf-energy.com. 86400 IN SOA dns1.cscdns.net. hostmaster.cscdns.net. 2019040337 28800 7200 1209600 86400

;; Query time: 28 msec
;; SERVER: 1.1.1.1#53(1.1.1.1)
;; WHEN: Fri May 29 11:31:48 BST 2020
;; MSG SIZE rcvd: 125

There's no A record for it.  Hence Virgin Media and some other mail servers may choose to reject the mail.

Tim

 

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JHam
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Re: Emails from specific address being bounced back

Hi Tim,

I have to say much of that has gone waaaay over my head! But basically you are saying the issue is more at the sender’s end? And VM are rejecting an email that gmail (my provider-husband’s emails get thru to me and I then forward it on to son’s VM) is happy to allow thru? 
it is strange that this has just started happening. Could it in any way be related to the fact that husband is wfh just now and so is “remoting” in to his work network and emails? 

Thanks, Jill

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ravenstar68
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Re: Emails from specific address being bounced back

Thing is, without seeing headers of previous sent mails that have succeeded, it's hard to guess which party is responsible for the change in behaviour.  However VM have a long history of blocking based on invalid reverse DNS,  I've advised other users of this before now.  To be frank, you'd expect a big company like the one above to know about configuring their outbound mail servers properly.

Tim

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