DNS configuration expert to help my newsletter not be marked as spam

I'm interested in sending newsletters only to people who opt in. I'm still having trouble being marked as spam. ## Deliverables My current configuration is as follows: . CentOS VPS . Zoneedit DNS management . phplist as e-mail manager Currently my configuration is not optimized. Even though users choose to opt-in, a lot of my emails are marked as spam. I need someone familiar with SPF, RFC, RBL, best practice e-mail policies etc. Importantly all diagnostics must be done WITHOUT direct access to my server. I can send test emails to your address if you want to examine the headers. The job is basically to tell me what I need to configure. I will do the configuration myself. The job will be considered complete once a user is able to subscribe to my newsletter and the confirmation letter can go to yahoo, hotmail, gmail etc without being marked as spam.