Fighting Spam

PaulZag writes about dealing with spam. I await with interest his approach he gave us a sniff of in a recent blog entry.

I thought I would share my experiences with spam.

First of all, I never use hotmail, yahoo or any other free email service. I’m not sure how, but it seems that these things are spam magnets and corresponding with people who have hotmail or yahoo addresses seems to make you a spam magnet too. So avoid these.

Secondly, I use an email alias. I use EasyDNS to host my hampel.com.au domain name and use their mail and web redirection services to point the relevant addresses to my free ISP web space and email addresses. So the address people send me mail to (hampel.com.au) is not the address where I actually receive the email – it is redirected to my ISP account (BigPond).

Now, the interesting thing I find is that the vast bulk of spam I receive (and I get a LOT of spam) actually gets sent to my BigPond account – which means that it is not coming from me entering my hampel.com.au email address into websites when I register for things – it’s coming from somewhere else.

I’ve discovered two things – a fair percentage comes from auto generated spam robots – where they invent email addresses and send them out blindly hoping that some will actually get to someone real. You can often see this in the email headers – there will be lots of other email addresses very similar to yours being targeted at the same time.

The other way I get most of my spam is from visiting websites, where they capture certain details about your computer from your browser and interpolate your email address from that. The worst thing that can happen is that you click on a banner advert on a web site (either deliberately or accidently), and that causes self-replicating pop-up windows to all sorts of sites (including adult sites sometimes !) – each of which capture enough details to be able to generate some spam at you. (The quickest way to extract yourself from this type of thing where windows open as quickly as you close them is to use the keyboard… Alt-F4 will close the current window… hit it quickly enough and you will close the windows faster than they can load their auto-load scripts).

Anyway, the upshot of this is that since most spam comes into my ISP email address, and not through the email address I actually tell people, I can actually effectively filter 90% of the spam I receive quite easily.

The remainder of the spam which does manage to get through on my personal email address, I deal with in a number of ways.

First, almost all of the people I correspond with regularly are in Australia – and the majority of them send email from a .au address – so any email that does not come from a .au address gets automatically moved into a “spam check” folder where I can verify who it is from and whether it should be read or deleted – without it cluttering up my inbox.

Secondly, I correspond regularly with no more than a couple of dozen people. For each of these people I set up a filter to move their emails into a folder specifically for them. This has three effects – firstly it makes it easy to see who I have mail from, since the folder for that person is highlighted when I get new email; secondly it keeps my inbox clean; and finally it makes it less likely that their emails will slip through into the spam traps I set – this is especially important for people who don’t send email from a .au address.

I did start down the path of trying to construct smart spam filters to automatically detect and delete spam, but it was only ever about 30%-40% effective at best, so I found it much more effective to create rules for those people who do send me email and filter their email out of the spam soup.

Now I do get the occasional person who insists on using dozens of email addresses (*cough* PaulZag *cough*), which does become painful since I need to keep adding filter entries for him everytime he uses a new one. But it’s still very effective, and make managing emails and keeping a clean inbox quite easy.

Just remember – the worst thing that can happen with a spam detection system is a false-positive, which means that you treat a legitimate email as spam and automatically delete it. So be careful with this type of thing.

Incidently, someone sent me a link today for an anti-spam device which some people may find useful. Mailinator