With Spam Assassin you can Check your campaigns/newsletters before you send them out, this is very useful as you will see your Spam Score before your campaign goes out, this in turn will enable you to make the correct adjustment to your campaig. 

When you have finished your creative and campaign and you are ready to send it out, use the Spam Assassin to check your spam score based on the content of your newsletter. The higher the score, the more likely your newsletter e-mail ends up in your subscriber's junk box. Spam Check provides easy-to-follow recommendations on how to reduce the likelihood of your e-mail being filtered.