Is ISP monitoring and sometimes subsequently blocking of transmitted email content illegal?

Peter Fairbrother zenadsl6186 at
Sat Apr 12 13:45:17 BST 2014

It depends.

If monitoring, including monitoring content, is done "for purposes 
connected with the provision or operation of [the] service" then it's 
lawful interception under RIPA ss.3(3).

For example, if an ISP monitors outgoing email in order to stop spammers 
that would be lawful, as other ISPs would blacklist them, and prevent 
them from sending email - the monitoring in necessary to ensure the 
operation of the service.

Another example is scanning for malware; when your computer is connected 
to the internet it is part of the telecommunications service, and the 
service might fail if the malware got through.

As to blocking email, I don't know of any legal obligation to deliver, 
or even try to deliver, email, but it may exist somewhere.

As to Mary's original question, I don't know what Demon might want to 
keep for its own purposes, but they were asked about this a few days ago 
and said they would get back, so maybe some answers might be forthcoming 
in due course.

Data retained might include service usage, types of service, preferred 
destinations and so on, all of which might be required to fine-tune the 

Though such information should be anonymised unless it is necessary not 
to anonymise it.

To give a made-up and totally spurious example, suppose you talk to 
Tuvalu a lot. They might want to know whether the traffic to Tuvalu 
comes from a few customers, or from many. They might want to change 
their peering arrangements (how they pay for traffic on other people's 
networks, and how they get paid for passing traffic from other ISPs on 
their network) with traffic to and from Tuvalu, eg if it's very 
expensive and only a few people use it then they might want to encourage 
you to go elsewhere.

Conversely, if you only use cheap routes they might want to offer you a 
better deal. They would need non-anonymised data for that.

All legitimate business reasons, though I doubt Demon keep any data for 
precisely those reasons... and probably very they keep little traffic 
data at all.

-- Peter Fairbrother

On 12/04/14 12:49, Peter Tomlinson wrote:
> The ISP that I use for sending email (and that is provider of my
> landline that also provides a traditional telephone service) definitely
> monitors message body text of transmitted emails because it blocks those
> emails that it claims contain unacceptable material. It seems that they
> use a service that has a black list of URLs that are not permitted in
> body text of emails transmitted by customers of the service - sometimes
> that makes it difficult to report emails containing or linking to
> malware. But they don't appear to monitor content of attached files that
> I send [1].
> They don't, however, apply the same monitoring and blocking to incoming
> email, as testified to by the operation of the Internet Security
> software that I use and by my not getting complaints that emails don't
> reach me.
> Peter
> Peter Tomlinson
> [1] So I can report a scam email by bundling its text and source code
> into a Word file.
> On 12/04/2014 12:12, Roland Perry wrote:
>> Although the ISP I migrated away from this week was definitely
>> monitoring my usage of email in case I was a spammer. The volume of
>> data was unlimited, but I could only send something like 500 emails a
>> day.

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