I write here couse I hope most of people from here are at disposal to inform their clients how to avoid spam.
I think it is no so bad idea if you are in resseling bussines to establish email list with you customers as a recipients and inform them about mostly known and active spammers.
And if you clients have something easy in use like CP antyspam functions - I think they will be gratefull you for that info.
lately I observe very strong spam activity with domain optinllc.com. The domain name is often used in message body as a link to some kind of tracking.
It is so easy set a condition "do not receive e-mails if the message body contains "optinllc.com" to and avoid spam.