Junk marked incorrectly in desktop Mac Mail

Several addresses always get marked as Junk. Some are Yahoo group emails, while others are mails from a single senders. Most are Yahoo mails, but some are iCloud mails, and others are Comcast emails. I am constantly marking them as not Junk. I also have added the senders to my address book, and have even reset my Junk filters. I've checked my accounts online, and they mark the mails correctly, so I don't know why mac mail marks them as Junk. Some incorrectly marked mesages go to my junk mailbox, while others go to either my inbox, or to designated folder, but there marked yellow. I've also noticed some mails in my Junk mailbox, although correctly placed there, not marked yellow and not designated as being Junk. Does anyone have any ideas how to fix this problem?