Email Filters Catch Dolphins Along With Sharks

What's the point in spending hours preparing a newsletter, message or report if it's automatically filtered into the junk folder before the recipient even sees it?

Spam threatens to choke the communication channels promising global freedom of expression.

Internet Service Providers (ISPs), corporate server administrators and end users are increasingly using new anti-spam technology to try to stem the relentless tide of junk email flooding the Net.

The problem is: how can we prevent the dolphins from being caught along with the sharks?

The origin of 'spam'

SPAM is a pink canned luncheon meat immortalised in Monty Python's spam-loving Vikings sketch.

In an Internet context, lowercase spam refers to unsolicited commercial or bulk email (such as get-rich-quick schemes, miracle cures, weight loss, Viagra, lotteries, loans, pornography and Nigerian sob stories) and allegedly originated in a MUD/MUSH community.

Of more practical use is the origin of the actual spam mail itself.

Where does all the junk come from?

In the mid-90s, Usenet newsgroups (also called "discussion groups" or "bulletin boards") were the number one source of email addresses for spammers.

Today, the most common origin is web pages, especially if they're listed in a search engine or directory.

Some people have tried foiling address-seeking spambots by inserting the word "UNSPAM" in capitals in the middle of all email addresses on their sites. This stops auto spammers working but enables human beings to work out what to do.

Spammers also harvest addresses from headers of messages you send to friends who forward them to their friends (a good reason for using BCC -- blind carbon copy rather than simple CC which displays all recipients - although some people filter out mail sent using BCC as many spammers also use it).

Other sources include open e-mail discussion lists and web pages that invite you to "insert your address here to be on a 'do not mail' list".

Spammers can simply guess addresses by generating lists of popular names and random words attached to common domains (bob@aol.com, john@hotmail.com).

Once on a spam list, the only way to get off is to change addresses.

If you reply or respond to instructions to "remove", your message will simply confirm your address is valid and you'll get even more junk.

Depending on your email client, you can try tracing junk back to its owner by contacting the server listed in the full message header information (the From address is generally fake - check your Help files to find out how to "reveal full headers").

How to stop spam

Despite legislation against unsolicited commercial email, the volume of junk is increasing alarmingly.

The simplistic oft-cited fix -- "just hit delete" -- is only a bandaid solution and fails to discourage the junk merchants.

Self-regulation and industry codes are difficult to enforce. ISPs face problems if they disconnect service to spammers under some countries' telecommunications laws.

Technical solutions have centred on filtering technology.

Types of filters

Many corporations and ISPs filter incoming mail on or after delivery.

Server-side filtering software typically looks at the headers, subject line and/or contents of the message.

Some filters -- and their users -- are smarter than others.

SpamAssassin is an open-source, collaborative, community anti-spam effort based on filtering rules to analyse email content.

The software gives each message a score based on how many rules it breaks.

Any programmer can suggest rules for new releases of the software which spots, not blocks, spam.

ISPs and server administrators then decide whether to send suspect mail to junk folders, automatically delete mail tagged as spam, or bounce it back to sender.

Unfortunately for email publishers, some of the filter rules are too broad or the threshold is set too low.

Many innocent messages are being lumped in with the guilty.

One of my newsletter readers notified me that his ISP had tagged a recent issue as spam -