Found out the two ways to make it sticky
Thanks for your reply, just like you said Akismet has identified those posts as spam. I contacted the user and asked for a report and he replied that every time he tried to submit the topic he got an error message stating “no subject”, which is strange since all five posts had a subject(the same). I understand if Akismet reacts on five messages in a row with the same subject in a short time, but the real question is why bbPress presents an error message when a subject is both submitted and inserted? Lets hope this will not happen again Maybe a one time error?