This seems to be true for the past two months, because there is an increasing number of people aware of it, they may eventually do something about it.

The problem

On one of my sites I have an address database with around 900 subscribers. This list has grown organically (people subscribe themselves) over 2 years.

A newsletter is sent out once per month and occasionally there are news alerts when we need to make sure people are aware of an event or meeting. This has worked without too many problems for several years. Until March of this year.

I found that around 17% of the subscriber base had rejected the messages from the server. Closer analysis showed that all of them shared one common attribute, they were all on BT or BT related email addresses. So btinternet.com, btconnect.com, talk21.com, openworld.com etc.  None of the other domains rejected the messages. 

I too have a BT email address, and while I have absolutely no filtering set up for my BT account the newsletter was rejected. BT had made a decision that I was not going to read that newsletter even though I had subscribed to it.

I read that Martin Lewis (http://www.moneysavingexpert.com) has also experienced problems from BT with his newsletter recently.

Take three valium and call BT

I pursued this with BT and spent over 3hrs with it. While I am not an expert on filtering, I have figured enough out about it over the past four years to guess what was going on.

Regretably after 3hrs the alleged “Support Agent” in India confirmed that even though he had witnessed that BT was filtering mail without my consent the BT system was working properly.

Evidence trail

When a mail is rejected there is normally a message that is returned. It does not always work, however in this case BT sent back a message that contained some information (I will not add it here, because it might cause this message to be blocked if you are reading it in a newsletter!).

The message relates to a device in the BT network that is analysing mail, this is not unusual, there are tests a service provider can carry out on mail to make sure it comes from where it claims it comes from, and a number of other things.

This device had detected something in the newsletter and for that reason rejected it.

I asked BT what the error message was referring to, then I could diagnose it. However I was told “We do not have any access to that department”. I have heard many excuses, but this one was the big corporate saying go away.  Every message had the same sequence of numbers, but without knowing what those numbers mean, it is impossible to diagnose it further.

Speculation

Having ruled out the normal reasons why mail is rejected such as blacklisting, and poor reputation, it points to something in the content of the message. In the BT case it was possible to send a message from the domain in question to my personal email account. So the sending domain was not being blocked.

I had one other case where something similar happened. In that case it was the word “medication” triggered some filter that stopped the email newsletter from going anywhere. In this case it was the hosting stopping it leaving the hosting so not quite the same. The logic was an email with the word “Medication” in might be selling online medication. Hence some bright spark had set up the device to look for that text and block it.

In this case it was a genuine newsletter from a nurse. Nurses may and do frequently refer to medication. I sorted this out with the hosting company in this case. But it took quite a few hours.

Returning to BT

They may be detecting certain keywords normally associated with spam messages. This does happen, and you may not be aware of it. It is a sledge hammer approach to trying to reduce spam.

More likely culprit

Filtering based on the number of links in a message. Some of the content aware filters that are in use by service providers may analyse how many hyperlinks are in a message and determine if there are too many then they will block it on the assumption that the message is SPAM.

Workaround

In my case, because BT were not listening, and could not help any further, or so they claimed I now only have OfCom to go to, to raise the awareness and get a more considered response.

I did the following on the website. Separated all of the BT addresses out of the whole database and placed them in a database of their own. So now on this site there is a BT subscriber list, and an Everyone Else subscriber list.

We continue to send the normal newsletter to the Everyone Else subscriber list without any issues. For the BT list we send a single link to the newsletter so they can view it on the web. So the email that is sent to BT users does not have dozens of hyper links in it, it has a couple. That so far has worked.

Other comments

I did some extensive searches on the error message and ultimately ended up on a BT bulletin board where many people were raising the same problem. I have spent much of my professional career in data communications, and I expect someone had decided to set some criteria up on a network device (content filtering switch) that will filter mail and has not tested it properly. The only metric they looked at is they are now handling less mail which was their goal. What they have not realised is that there are a lot of people affected by this, in some cases small businesses, and legitimate email is being caught as well as spam.  Worse still they are not listening, or we, the public have no way of reaching them to let them know. I expect as the noise gets louder they will eventually sort this problem out.