I still could not find the exact cause of why when one selects deliver all spam still it goes to dev null.
I did all quite as virtualmin defaults. YET i think its SA that needs an optimum config.
I have resolved for now by increasing score to 14 eg n any mail above that score is going to dev null.
I need to study SA more as it has some uncommon features that are not in default. If i find i will post.
FYI Virtualmin and webmin system as is - is perfectly setup and humanly the best functionality.
Rest is upon how we configure each part.