SMG - spam and Delete message on 4 of 5 recipients

Dear All,

I'm using SMG software version: 10.6.4-3, on Message Audit Logs i have an email with 5 recipients and it says Verdict: spam and action: Delete message on 4 of them but only one(the fifth) received the message with action delivered normally, may i ask how SMG decide who will receive the same message and who no.

Thank's