The spam score of your message is generated using Spam Assassin, the largest open source email content checker on the web. This score is a guideline, and should not be considered definitive regarding inbox or spam folder placement. The lower your spam score the better. ONTRAPORT won’t send any emails with a score of 5 or higher.
From the knowledge base:
The ONTRAPORT Email Builder is equipped and integrated with SpamAssassin spam scoring. This program works as an email/spam filter and uses sophisticated spam detection techniques to scan your emails before they go out and points out aspects of your emails (whether it be content, links, the subject line, the from address, or anything else) that may universally be considered spam by email and internet service providers. The higher the amount of spammy/questionable content, the higher the spam score. This in turn gives you a chance to further edit your emails before you send them to your contacts and ensures superb email delivery for us and you.
The lower your spam score the better. ONTRAPORT won’t send any emails with a score of 5 or higher. Anything above that runs a high risk of delivery issues and filtering of your message by ISPs. That isn’t to say that an email with a spam score of 5 or below is guaranteed not to be filtered everywhere, but it highly reduces the likelihood of any delivery roadblocks.