There’s a lot of news out there in the email marketing world. One place you can go for a summary of just about everything that’s ever been said is Tamara Gielen’s Email Marketing Best Practices blog. I don’t know how she can get so much information posted in one place. Seriously, just go ahead and bookmark it, or subscribe to the RSS thingy.
Here’s a list of 15 tips to improve your email deliverability (especially work on numbers 10-15).
We’ve also got an article on "How Spam Filters Work" over at MailChimp.com. Before you get into specific tactics, it’s good to learn how they work in general.