Hello Sudhakar,
You are correct. I apologize for the misinformation. I was apparently thinking of a custom project I was involved in where we created an own fact-gathering service and custom attribute for "is spam". But there is no such attribute in the default delivery. I suppose what you could do is to create an own rule that checks whether the email subject contains the term "spam" which presumably would be added by your spam filter which would append e.g., "likely spam" at the beginning of the subject line.
Warm regards,
John