There are lies, damned lies, and statistics, goes the old phrase. You could equally well replace the word 'statistics' by the phrase 'opt-in email lists'.

While doing some tidying up, I came across an article from The Register. The author describes how he received spam from T-Mobile and decided to trace it back to its source. What he found was that T-Mobile's marketing company had bought an email list from another company ... which bought it from another company ... which bought it from someone on eBay.

Naturally, everyone involved swore up and down that the list was 'opt-in' only. How did they know? Well, the previous person in the chain — starting with Colin on eBay — had assured them it was. Colin, presumably, had generated this 'opt-in' list with the aid of tools that picked out the addresses of people who had 'opted-in' to receive mail by putting their addresses on their websites, posting to mailing lists, exchanging mail with people who have viruses on their PCs, or any of the other thousands of ways it's possible to 'opt in' to receive spam these days.

Most of the spam I get is the usual disreputable chaff - pills, penny stocks, and penis enlargements. However, a substantial proportion also comes from what are probably 'legitimate' businesses, including some household names. In many cases, the company would probably be horrified to know that their promotions are being sent out as spam — not necessarily because big business is more ethical, but simply because successful businesses are usually astute enough to recognize the negative impact of spam on their reputation and their bottom line.

Where businesses aren't so smart, however, is in blindly accepting the assurance that the marketing company they've just hired only sends to opt-in addresses. If you're a business looking to hire a marketer and someone tells you that, look them in the eye and say Bullshit. You'll be right more often than you're wrong. In fact, I'd guess that you'd be wrong less than one time in a thousand.

Want to know what an 'opt-in' address looks like? It's one that you collected yourself and then confirmed with the user. Any other 'opt-in' address you are offered probably had an encounter with a guy called Colin somewhere in the past and leads to an unhappy user who's going to hate you forever and stick pins in a wax doll of your CEO if you send them anything.

But wait &mdash am I saying that there no legitimate 'opt-in' mailing lists in circulation? Are there no bulkmail companies whose mailing lists are squeaky clean and only send to users who really want to get your announcements and special offers?

It's possible. Just possible. Unicorns may exist somewhere too, although I've never seen any.

If someone offers you an 'opt-in' mailing list, they're asserting that all the addresses on that list belong to users who are happy with the idea of receiving email from anyone and everyone. Lists of this kind can exist in niche markets. For instance, a journalist might sign up to get industry press releases. They aren't going to get upset when they get an emailed release from a company they never heard of because digesting press releases and spitting them out as next week's column is pretty much their job.

Similarly, there are companies that offer what you might call 'willing spam victims': a user agrees to read a certain number of emailed ads per month in exchange for cash or services. Those can also be legitimate, but before you trust your good name to such a company, do a little investigation. Search Google for signs of dissatisfied customers. Sign up for their list yourself (using a throwaway address) and see what it's like to be on the receiving end. Do they stick to the agreed limits? Do they handle the mailouts themselves and mark each advert clearly, or do they just sell the user's address on to the advertisers and let them spam away? Is it easy to get off their list when you've had enough?

Finally, there are companies whose mailing lists consist of people who have 'technically' opted-in. Somewhere on a website there was a checkbox that said By clicking this checkbox, I agree to receive mail containing promotions and special offers from ______'s partners and affiliates.. The owners of the addresses on lists compiled this way have indeed 'opted-in' (although the odds are good that they didn't confirm opting in, and that's a vital distinction). But the chances are that most of them didn't read the small print carefully enough and didn't anticipate that it would lead to them getting email from everyone and their little dog. Half of them probably don't even remember checking that box and don't understand why they're getting all this email they never asked for. Whether they 'opted-in' is irrelevant here. What matters to you is whether your ad showing up in their inbox is going to make them want to throw rocks at your storefront.

The message is simple. Distrust any mailing list that you didn't collect yourself in the most meticulous and respectful way possible. Ultimately, it's your reputation that's at stake. If you're a big business, you pay a small army of PR people, image consultants and lawyers to keep everything looking shiny. Don't throw that all away by blindly buying a mailing list from someone who did business with Colin.