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One Third of Email Now Spam
Himanshu writes "The volume of spam received by business has doubled over the last two years and it's going to get worse.
Analysts IDC reckons that spam represented 32 per cent of all email sent on an average day in North America in 2003, doubling from 2001. That figure is less than the 50 per cent or more junk mail statistic commonly cited by email-filtering firms like MessageLabs and Brightmail but it still represents a serious problem,"
From the logs of our anti-spam appliance, over the last six weeks or so:
That's right, about 96% of our email is spam, viruses, or otherwise ungood.I'd be delighted if the spam dropped off so it were only 32% of our mail. Think of all the things I could do with that extra bandwidth...
In fairness, the study says they were looking at businesses, and this is at a small ISP, mostly residential customers. But it's a good number to chew on nonetheless.
Comment removed based on user account deletion
I heard about it here on /. and installed it the same day. At first it marked ALL my mail as spam because I'm on a few list servers, but the adaptive learning function of it is getting much better. After I "unlearned" my list mails as spam, it'd still let about 60% of spam through. Now it gets about 40 out of the 42 spams I get a day. I don't mind deleting two (or hitting "j" for junk), and recent searches through the junk folder show no false positives.
Check it out...
Stick a mail proxy between the internet and Exchange, that way he still gets to keep using Exchange, and you have a simple proxying machine that can do arbitary scanning and filtering.
You can scan all incoming mail with spamassissin and clamav before it reaches exchange, bounce or drop bad mail and forward "passed" mail into the Exchange server
You could also hookup a challenge response script there too.
I do the same thing for a company mail server running Lotus Notes.
Filtering is removing about 97% of the spam, but even after filtering, I'm getting more spam than real mail.
Most of the spam seems to be selling prescription drugs. It's clear the Bush Administration doesn't want to do anything about this; there's plenty of authority for stopping illegal sales of prescription drugs on-line. Prescription drugs are traceable, after all.
Ran into this same problem at my company... Tested two different things out:
Mailwasher - Not a challenge/response like you asked for, but allows you to send bounces back to spam, and delete them off of the server before you donwload them. Can tie into SpamHaus and such.
ChoiceMail - Challenge response, both single user and enterprise are available. Single user sits on local machine, enterprise ties into Exchange. Can quickly add anyone in your Outlook contact list to the whitelist, and anyone you send an e-mail to can be set to be whitelisted. The challenge message can be customized. Biggest problem with the bounce (at least in my testing) is that the challenge gets rated as spam by my filters. I'm sure if the challenge was tuned up it wouldn't be that big of a problem. And they have a free trial so you can test it for 14 days
Nephilium
Why has nobody realised yet that it doesn't say 1/3 of email recieved is spam, but that 1/3 of email sent in the US is spam. I'm not suprised at that in the slightest - most spammers don't want to bother with the legal risks involved in sending spam inside the US. Just send it through some open relay wherever you find one or operate from Russia, it's far easier.
Can anyone suggest a decent, doesn't have to be perfect, server side anti-spam filter?
/etc/access file such as: "connect:218 REJECT" will knock off about 200-5000 spams per day utilizing minimal system resources).
2 ,210,211,213,217,218,219,220,221 and you'll stop a TON of spam from a lot of foreign countries you likely never communicate with.
Don't waste your time implementing a content-based filter. The best solution is to incorporate a real-time spam relay blacklist. I recommend bl.spamcop.net. It's very effective and accurate with an extremely low legit mail blocking rate.
RBLs are great because they refuse spammer connections before the mail even gets delivered, so you don't waste bandwidth and system resources downloading spam crap and trying to interpret the contents. RBLs respect the sanctity of the e-mail message as a private communication medium and penalize those ISPs which allow spammers to operate.
If you're using Sendmail, you can also hard-code some of the IP regions where tons of spam is originating (signal-to-noise ratio for most people on the Chinese IP blocks is 0% so why allow them to hit your server in the first place? A few lines in your
Personally, if you want to get aggressive, block the following Class As: 61,80,81,82,83,142,164,193,194,195,196,200,201,20
Set up a web-based e-mail form and put a link to it in your Sendmail access configuration so that if any legit mail gets bounced, they can redirect to a web page to contact you in the [unlikely] event they were inappropriately blocked.