Have you noticed how many more organisations are harvesting e-mails from websites and using them to send unsolicited mail? Most days at the moment I spend time unsubscribing from a newsletter that I didn’t elect to join.
MAPS have some clear guidelines for managing e-mail list which are worth reviewing if you are sending out a newsletter or any other kind of e-mail circulation. You’ll find these guidelines at http://www.mail-abuse.com/an_listmgntgdlines.html. MAPS is a major anti-spam blacklist service.