Spam filter

[#1]

Anybody know why the Plusnet spam filter is relatively ineffective? The filter I have with my Macmail programme works a treat on my laptop, but the the Plusnet one is weedy, which is a nuisance when I'm reading webmail on my mobile on the road.
I have followed all the guidelines on the Help site and I keep tagging items as Spam, but then I still get Spam coming from the same address.
The odd thing goes into my Spam folder but not much.

[#2]

Hi there,
Our spam filtering is trained on a global level (ie. the same rules are used for all customers) whereas the Macmail filters you're using will be tailored specifically to the messages you receive. I would always expect a local anti-spam solution to be more accurate than anything that can be supplied at the ISP level.
Forwarding emails to the training addresses ensures that the false positives and negatives you receive are made available to the training engine. Only a subset of these messages are used each day though.
Are the emails you're receiving all from the same source or very similar in content? If they are I might be able to ensure a few of them get pushed through the training system.

[#3]

How do people like Google filter there GMAIL accounts so well?
I would assume that because they have millions more customers of GMAIL there spam filters will be trained to near perfection.
My domains are still screwed from when Plus Net leaked the details(or whatever happened way back when they first got attacked).
James Barlow

[#4]

Quote from: jabns2

How do people like Google filter there GMAIL accounts so well?

They use (at least) a two-pass filtering system.  One at the global level to detect spam, and one at the personal level for your identified spam

Quote from: jabns2

I would assume that because they have millions more customers of GMAIL there spam filters will be trained to near perfection.

No, because different people class different things as spam. 
Imagine if a group of chemists all had email addresses with Gmail, and were discussing Viagra.  Their mails consistently get put into the spam folder, so every time that happens they forward it back onto the filter saying 'this is not spam'.  Meanwhile, hundreds of other people are forwarding mails containing the word 'viagra' into the spam-training filter.
The best idea is to do exactly what Google do - they have an overall spam filter which is very permissive.  It actually allows quite a lot of spam through.  It only takes out what is 100% definately spam.
Then, on the next pass it applies personal rules to the spam and filters out whatever matches those rules.
Unfortunately, having personal spam filters at the ISP level is not cost-effective for most ISPs.  Google is able to do it because they have pioneered massive-cluster technology and have plenty of cash to throw at it.
The best way is to rely on the ISP to do 'top level' filtering - taking out what is 100% guaranteed to be spam, and leaving the rest to a personal filter - either something like Thunderbirds built-in spam filter, or Mailwasher for example.
B.

[#5]

Quote from: jabns2

How do people like Google filter there GMAIL accounts so well?

Probably because they're in a position to invest a lot more time and resource into manually training their filters. They also didn't suffer the database compromise like we did. I know Dave's got a novel conspiracy theory about the former - I might see if he's willing to share it with us!

Quote

I would assume that because they have millions more customers of GMAIL there spam filters will be trained to near perfection.

A larger volume of mail would help, but we're certainly not short of spam ourselves!

Quote

My domains are still screwed from when Plus Net leaked the details(or whatever happened way back when they first got attacked).

Is the spam getting sent to your domains or your .plus.com address? Have you set up individual mailboxes and had your catch-all switched off?
Edit: I see Barry's now posted providing a bit more detail on the mechanics of Google's filtering.

[#6]

I redirect some spammed, but previously used addresses to a Gmails address. Then I forward them back to an F9 address which I have not used for anything else.
It's really effective because Gmail keeps the spam and sends me back the ham - and it's good at it.
Tony

[#7]

Hi, Bob and others! Thanks for replies. (Been away). What is certainly frustrating is that most of them do come from a limited number of sources - I send them (manually) to my spam folder, then report them, then trash them (which I've just done for over 100 accumulated over three days) and still they keep  coming, clogging my webmail on my mobile. I would certainly appreciate a bit of pushing things through the system.