Menu
Reply
  • 17
  • 0
  • 5
Philhynes
On our wavelength
192 Views
Message 1 of 11
Flag for a moderator

emails from another domain not arriving but no bounce-back message

There are several threads on this forum about emails being bounced, but they all seem to refer to a bounce-back message. The problem I have involves messages apparently disappearing into a black hole. emails sent from one specific domain (on a webhosting service) to email addresses on ntlworld are not arriving, but nor is any bounce-back message being received to say that they have been rejected. Can anybody suggest an explanation? The intended recipients do not find them in their Spam folder. It is most worrying because the sender is not aware that the messages have not been delivered.

0 Kudos
Reply
  • 8.36K
  • 954
  • 3.67K
Superuser
Superuser
177 Views
Message 2 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

In the absence of any other information like "bounce" messages the start of this process must be for the sender to ask to see the ESP's sent mail logs to see if the mail was in fact sent and what happened to it afterwards. There can be no assumption that VM are at fault here unless the logs show the mail was successfully sent and successfully received by the sender's outgoing mail servers and VM's incoming servers respectively.


-----------------------

Superuser 2017/18
Use Kudos to say thanks
Mark answer as "helpful" only when the problem is solved
Please don't send me private messages unless I ask you to.
I do not work for VM. The advice I give is based on my best understanding of VM policy and practice. You rely on it at your own risk.
  • 17
  • 0
  • 5
Philhynes
On our wavelength
152 Views
Message 3 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

Thanks for the advice. My ESP has investigated further and reports that their server's IP address was 'blocked' at cloudmark.com. I presume that VM use this system for monitoring incoming emails? Apparently, in the recent past, an email forwarder on my ESP's server was forwarding spam so the whole server was blacklisted. Action has been taken to prevent further spam being forwarded, but it takes time for other email services to recognise that the server can now be trusted. The aspect that surprises me most is that no rejection message is returned to the sender. I suppose that VM thinks that the emails are spam and so discards them, but it is disconcerting that the email sender has no way of knowing that their emails are not reaching their destination.

Phil.

 

0 Kudos
Reply
  • 8.36K
  • 954
  • 3.67K
Superuser
Superuser
146 Views
Message 4 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

Your surmise is broadly correct. I am surprised that the sender (you?) got no bounce messages. Let us see what the VM Forum Team say when they reach this thread in the next week or so. In the meantime we can but hope that the server clears from Cloudmark's bounce list.

-----------------------

Superuser 2017/18
Use Kudos to say thanks
Mark answer as "helpful" only when the problem is solved
Please don't send me private messages unless I ask you to.
I do not work for VM. The advice I give is based on my best understanding of VM policy and practice. You rely on it at your own risk.
0 Kudos
Reply
  • 15.67K
  • 868
  • 5.84K
Superuser
Superuser
138 Views
Message 5 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message


@Philhynes wrote:

Thanks for the advice. My ESP has investigated further and reports that their server's IP address was 'blocked' at cloudmark.com. I presume that VM use this system for monitoring incoming emails? Apparently, in the recent past, an email forwarder on my ESP's server was forwarding spam so the whole server was blacklisted. Action has been taken to prevent further spam being forwarded, but it takes time for other email services to recognise that the server can now be trusted. The aspect that surprises me most is that no rejection message is returned to the sender. I suppose that VM thinks that the emails are spam and so discards them, but it is disconcerting that the email sender has no way of knowing that their emails are not reaching their destination.

Phil.

 


You'd suppose wrong.  Virgin Media don't simply discard emails.  When you ESP says they're "blocked at cloudmark.com"  Can they explain.

1.  How they came to this conclusion.
2. If they have any actual error messages in their server logs.  If so could we see at least one of them errors (don't post any full email addresses though).

Their server has been known in the past to send a 4xx error back to a mail server,  Which would cause the sending server to defer delivery up to the point where the retry queue expires.  At which point the sending server will bounce the mail.

Likewise  - If Virgin Media reject a mail at any point in the email transaction, the sending server will deliver a bounce message.

If Virgin Media have accepted the mail and then discarded it then the sending server would in fact get a 250 status code (which essentially means the transaction was successful)  Again even seeing a successful send would be beneficial here as the receiving server also gives the message ID it created for the incoming mail as part of the success message,

Tim

________________________________________


Only use Helpful answer if your problems been solved.

  • 15.67K
  • 868
  • 5.84K
Superuser
Superuser
131 Views
Message 6 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

Note as well that on occasion there has been a delay on Virgin Media's internal network after they've accepted the mail.  However in those cases the emails do appear several hours later.

I've done a quick check sending to my blueyonder address from my own domain, the message got through straight away so I don't think that's the issue on this occasion.

Tim

________________________________________


Only use Helpful answer if your problems been solved.

0 Kudos
Reply
  • 17
  • 0
  • 5
Philhynes
On our wavelength
97 Views
Message 7 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

My ESP say they have taken remedial action to clear this problem, but so far my messages from their server to an ntlworld email address still aren't getting through. They have sent me this extract from a log to show the Cloudmark problem:

Dec 5 21:31:22 wordpress4 postfix/smtp[1526558]: 0121F42D74: to=<xxxx@ntlworld.com>, relay=mx.tb.ukmail.iss.as9143.net[212.54.56.11]:25, delay=0.37, delays=0.27/0/0.09/0, dsn=4.0.0, status=deferred (host mx.tb.ukmail.iss.as9143.net[212.54.56.11] refused to talk to me: 550 mx2.tb.ukmail.iss.as9143.net mx2.tb.ukmail.iss.as9143.net logid=SMTPRC 550 MXIN103 Your IP 5.77.55.219 is in RBL. Please see http://csi.cloudmark.com/reset-request/?ip=5.77.55.219 ;id=UelOgN7OTJ8A9;sid=UelOgN7OTJ8A9;mta=mx2.tb;d=20181205;t=223122[CET];ipsrc=5.77.55.219Smiley Wink

They also say this extract shows that the problem has been cleared:

Dec 6 10:11:46 wordpress4 drweb[1996366]: Starting the drweb filter...
Dec 6 10:11:46 wordpress4 qmail-queue[1996366]: scan: the message(drweb.tmp.wLaNWW) sent by xxxx@xxxxclub.co.uk to xxxx@ntlworld.com is passed
[root@wordpress4 ~]#

I don't understand the logs, but my messages still aren't being received! I do understand that it can take some time for clearance to take effect, but I also don't know why I'm not getting any rejection messages.

Is there any way I can get my ESP to discuss this directly with somebody at VM instead of me acting as go-between?

Phil

0 Kudos
Reply
Highlighted
  • 15.67K
  • 868
  • 5.84K
Superuser
Superuser
80 Views
Message 8 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

 If the problems fixed then your ESP should have actually been able to show a successful delivery..

Reading the logs is actually easier then you think.  I'll break it down.

Dec 5 21:31:22             - Date and time of log entry.
wordpress4                   - Host name
postfix/smtp[1526558]: - Process name and ID

Now we get on to information about the mail itself


0121F42D74:                   - mail queue ID - This can be useful for tracking a particular mail when delivery is attempted several times. or even an incoming mail at different stages in it's processing.
to=<xxxx@ntlworld.com> - Intended recipient.
relay=mx.tb.ukmail.iss.as9143.net[212.54.56.11]:25 - The host name and port that the server was attempting to deliver mail to.  In this case Virgin Media's inbound mail relay.
delays=0.27/0/0.09/0 - This shows delays in message processing for example connection and transaction time as well as the total time the message has been in the queue.
dsn=4.0.0 - Delivery status notification code - this is odd - I'll explain why later.
status=deferred (host mx.tb.ukmail.iss.as9143.net[212.54.56.11] refused to talk to me: 550 - status of send deferred means that the mail will try another time.  Other possibilities are sent and bounced (in fact I would have expected this to fall into the latter category)

Note as well we see the actual error message from the server:

logid=SMTPRC 550 MXIN103 Your IP 5.77.55.219 is in RBL. Please see http://csi.cloudmark.com/reset-request/?ip=5.77.55.219;id=UelOgN7OTJ8A9;sid=UelOgN7OTJ8A9;mta=mx2.tb;d=20181205;t=223122[CET];ipsrc=5.77.55.219Smiley Wink

I'll state unequivocally - this mail was rejected by Virgin Media.  The server actually sent back an error code of 550 in response to the connection attempt.

It was saying "There's no way I'm talking to you - your server is blacklisted - (It isn't any longer I've checked)

And here it gets odd because the dsn and status don't match what should have happened.

5xx errors are fatal errors  They indicate that a transaction has been rejected.  Temporary errors are indicated with 4xx codes and successes with 2xx codes  (Typically 250 message accepted at the end of a transaction)  The first number of the dsn code SHOULD match this. and it doesn't

dsn=4.0.0 - indicates that your forwarding service treated this as a temporary error (indeed blacklisting can be as server admins do work to get their IP addresses removed ASAP) which doesn't match the status code that Virgin Media sent back.

In short this message was rejected by Virgin Media but the forwarder decided to try again later anyway.

I'll have to read up on best practices for managing being blacklisted, but this to me appears to be bad practice on the part of the forwarder.

You could ask the Forwarder to contact Virgin Media via the standard postmaster address (if they know their job they'll know it as there is an established convention for this in the RFC's)  Alternatively they could post in this thread directly if they have the ability.  But it can take the Forum team a few days to get to threads.

BTW the second log excerpt proves nothing.  Can you ask them if they can see any successful DELIVERIES - status=sent in their logs.

Thanks

Tim

________________________________________


Only use Helpful answer if your problems been solved.

  • 17
  • 0
  • 5
Philhynes
On our wavelength
74 Views
Message 9 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

That's a lot of information and I'm grateful to you for responding so quickly. I'll be getting back to the ESP to try to follow this up, but it sounds as though my emails might start working once the blacklisting has been lifted. Exactly why we were blacklisted is another story - the suggestion is that it's because we had email forwarding switched on and were forwarding spam. This may not be the full story, but if it is the explanation then it suggests that spam filtering on our incoming mail was not doing a very good job!

I doubt the story will end here, but once again thanks for your help.

Phil

0 Kudos
Reply
  • 15.67K
  • 868
  • 5.84K
Superuser
Superuser
69 Views
Message 10 of 11
Flag for a moderator

Re: emails from another domain not arriving but no bounce-back message

The thing is it might not be your mail that caused the issue - remember Forwarders often forward mail for many users, so it's not uncommon for this sort of thing to happen.

I don't like forwarders for all sorts of reasons (they offer a good service but changes to the way mail works means that you can end up with delivery problems for other reasons as well).  I prefer to either use a professional email host to receive and store my mails, or to run my own email server.

Tim

________________________________________


Only use Helpful answer if your problems been solved.

0 Kudos
Reply