On March 10th, the Messaging, Malware and Mobile Anti-Abuse Working Group (M3AAWG) published a new version of the Senders BCP (Best Common Practices) document -- a solid overview and set of recommendations on how to not be a spammer.
They're not particularly rough or tough recommendations to follow. If you're not a spammer, you're probably following most or all of them already. They outlay good/better/best recommendations for opt-in permission. They explain that email append is unacceptable. They say that subscribers should never unknowingly end up on a mailing list. It should always be easy and simple to unsubscribe. Be transparent in what you do as a sender. Again, this is not earth shattering stuff, but it is good to see it published in a good industry forum, in an easy to digest format.
Do these recommendations matter? Yeah, because just about every mailbox a sender is going to want to send mail to is hosted by an ISP or company represented in M3AAWG. It's a pretty clear guide to what the rules are.
(H/T: Josh over at Word to the Wise)