Cannot get rid of junk mail. I delete it then empty trash and it comes right back to junk mail folder.

E-mail provider and is the account(s) IMAP or POP? If IMAP, try going to Mail/Preferences/Accounts/Mailbox Behavior and check the box for Store Junk Messages on Server.

Try changing it to something else and test. If this is with Gmail, others are having the same problem. Look at the 'More Like This' box at the top right.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

Mail/Provide Mail Feedback

You should check your settings for junk mail in preferences (in all accounts logged into the mail feature) and make sure you got the setting of storing your junk mail in the server turned off and also the setting of when to delete junk mail to be on something like after a month or week or when you quit mail, anything but "NEVER".