Email marketing is not just spam, it is an important way of updating and maintaining a relationship with your customers. For many however it is a black art (literally) plagued by blacklists and emails disappearing into black holes. The various explanations for failed email delivery however are often highly technical and involve trial and error to resolve rather than guaranteed solutions.
The first resource that I created is a 1 page document to explain the problem areas in the email delivery process. It is simply entitled Email Delivery Explained (click to download the PDF). It is by no means comprehensive, but it is instead targetted at first time email marketers and budding e-sales people trying to understand the world of email marketing. If you found it interesting and want to know more, or want a great email marketing provider, then check out the MailChimp Resources page.
The second resource is a very cool program called Litmus. This software validates your email marketing collateral against the various email clients (desktop clients such as Outlook and Lotus, as well as web based clients like Hotmail and Gmail). It will provide a visual image of exactly what went wrong and where, so you can keep tweaking until it looks right. Not only will it improve your email marketing presentation, it will also check the content against spam filters like Norton, SpamAssassin and many others. You really can’t be much more thorough than that!