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Originally Posted by badnbusy
Might be to some, but....the problem is - NO spam filter is 100% accurate. So...what happens to the emails that get accidentally caught (and probably deleted) by mistake. You will never even receive the email as it will be killed at the server.
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Fully agree with the virus scanning though. Good job ntl...
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Originally Posted by How accurate is the filtering?
The first and most important measure of the accuracy of any spam filtering system is that the number of genuine e-mails wrongly identified as spam should be as close to zero as possible. There is, however, always a very small chance that a non-spam e-mail will trigger a filtering rule by mistake - this is known as a "false positive". Brightmail claim a false positive rate of just one per one million. This means that if the system decides that a mail is spam, then it is almost certainly spam.
The second measure of accuracy is that the number of spam messages that escape the filtering system (a "false negative"), should also be as low as possible. However, because the primary objective is to reduce the number of false positives to almost zero, it does inevitably mean that some actual spam will slip through. Brightmail claim to be more than 90% effective in identifying spam. For more information see the Brightmail website
No filtering system is 100% effective at identifying spam e-mail. If your address is targeted before Brightmail has set-up rules to recognise a particular piece of spam (Brightmail claims to update their rule-sets within a few minutes of seeing a sample), then you'll be unlucky enough to receive some spam. Demon believes that this is a very effective spam-filtering system and recommends customers use it to reduce the volume of unsolicited e-mail.
Please do NOT contact Demon Support if you do still receive an occasional e-mail which is spam. Whilst the Demon anti-spam filtering service should detect most spam, it is not guaranteed to remove all such messages. You can, however, help to further improve the accuracy of the filtering by submitting copies of unfiltered spam, or legitimate e-mail incorrectly identified as spam, to a special forwarding address.
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Demon put brightmail antispam on their mailservers last year about 6 months before I finally cancelled all my demon mail services and let me tell you it's fab.
Brightmail use no auto filtering, but manually parse to generate rules for new spam (so some numpty who cannot be botherd to unsubscribe from the ebuyer mailshot cannot get that turned to a spam rule at the click of a button). They also have many many unannouced mail boxes setup across the internet on most ISPs. As the existance of these boxes has never been published, if a mail arrives in one of them it must be unsolicited and a rule is then generated.
Because of this a more spam will get through than some more aggressive applications, but the 0 false positive is the result NTL are looking for, not 0 spam.
IMHO NTL have the right spam package in place, if it works as well as Demons you will be very happy mail users, oh and I think Demon found it reduced mail traffic by 40% and thus extended the life of their mail servers by another couple of years.
This is the Demon FAQ on the matter, I imagine NTLs implimentation will be similar.
http://www.demon.net/helpdesk/faq/spamfiltering.shtml
With the demon implementation it was certainly rolled out, some of my accounts being filtered weeks before others, when I asked they said it was to ramp up the utilisation of the filtering servers gradually and ensure they were stable as more accounts were punted through them, rather than flood them and have the whole mail system collapse.