I am using Spamsieve 2.9.23 with El Capitan 10.11.2 with Apple Mail following instructions and have a few problems.
When I select messages and mark them as spam they end up in the junk mailbox, not the Spam mailbox I created.
Mail will not let me delete Junk mailboxes as specified in the instructions. There is the overall Junk mailbox and under it a Junk mailbox for each of my email accounts.
In one email account, a gmail account, When I mark a message as spam, it changes color, disappears for a couple of seconds and then reappears again in the original account mail box. Doing it again it stays moved. IOW, I have to key cmd-ctrl-s twice to move it out of the account mailbox.
What have I done wrong?