How can legitimate opt-in list publishers avoid getting their mails caught in spam filters? The key is to avoid getting your initial email caught in the filter. Bayesian filters "learn" about spam characteristics from the mail each user receives. Once a mail ends up in the spam folder, all mails resembling it will be classified as spam. Which means once you get in the spam folder, you won't get out. The opposite is also true, however. If the recipient discards your email as ordinary trash, he thereby labels it as legit, and mails resembing it will in future get past the filter. So the key thing for the legitimate publisher is to avoid getting that first email classified as spam. If you can get the first email into the inbox, and the user doesn't mark it as spam, you're in. How do you do that? Avoid saying spammy things in that first email. Sales pitches, for example. And even more importantly, include words that only a legitimate sender would know, like the first and last name of the subscriber. If your list, like many lists, is related to some specific interest that the subscriber has (model trains, for example), use terms related to that field as well, because they will likely have occurred in his legit email already.