How are opt-in e-mail lists distinguished from spam lists?
 

Someone I know sends advertising to an opt-in e-mail list. (We'll assume the list is what he says.) Unfortunately, the messages appear to be getting blocked. I tried to explain to him how the e-mail system works, but I really couldn't explain how companies (mostly big ones) can send ads to their customers with no problem. Is it that recipients don't mark it as spam, special formatting, or a special agreement with someone? I noticed that Spamhaus won't whitelist e-mail advertisers of any kind.

Note: I realize this is a potentially controversial thread. If you don't like what this person is doing, the best you can do is try to give me convincing reasons this will never be successful. Just don't get mad at me for what other people are doing.

How does the e-mail system distinguish an opt-in list from a harvested list?

The short answer is that there is no obvious way to distinguish between spam and a mailing list. The only difference between unsolicited advertising and opt-in advertising is the subscription list; the email system has no way of accessing such a list, and even if it did, no way of verifying its accuracy.

The way spam is distinguished in practice is through a number of factors including: the content of the message; illegitimate message headers; the number of recipients; and even the response of the recipients (for example, gmail users can mark messages as spam).

When sending messages to a list, one cannot just assume that opt-in is a blanket and in-perpetuity licence for advertising. A successful newsletter will contain useful content (not just advertising), will be infrequent, will have a valid reply address, will have an easy one-click method of opting out, will not contain tracking links, and so on.

The ideal spam filter would reject any email we don't want to receive, regardless of whether it is "opt-in" or not. So when sending mass emails, the key is to sending an email that you know that all the recipients will want to receive; if in doubt, don't send it, or weed the list.

The companies that send advertising are only successful when they respect their customers and are conservative in their email practice. There are no conspiracies or special agreements.

Thank you for the thorough and dispassionate reply.

First, the content of the message can be evaluated and refined using certain tools, and obvious fooling around with things like headers is a giveaway. So, I think these factors can probably be taken out of consideration.

What you seem to be saying is that when Amazon sends a blanket "get Amazon Prime" e-mail, they are as vulnerable as anyone to have the message discarded. But don't we all get e-mails like this? How can their success be explained?

Amazon and such companies mail in bulk. Perhaps it is the reputation that Amazon has built from the e-mails that people didn't mark as spam?

I dunno, it just seems like there's some further explanation.