junk folder in mail app (using MacBook)

i'm using MacBook and the mail app send some mails directly to the junk folder despite the fact that the filtering setting is already turned off.

i sometimes mark the mail as not a junk and send it to the inbox folder but later on when the same sender send me something the mail app ridiculously send it again to the junk folder!

is there anyway i can fix this error or anyway to delete that junk folder so that the mail app can understand that i don't like any mails to be sent to the junk folder.