Junk mail is freezing Mail.app

Have you tried (in mail/preferences/junk mail) to tick the "enable junk mail filtering/when junk mail arrives..."perform custom actions", then you need to select "advanced" at the bottom and from the new window, "perform the following actions" then select "delete".

That should work for future junk.

Also, have you tried (you could try this first) "rules" (also in preferences) and do an "add rule" if mail is junk mail, then delete.
Then you need to "apply", hopefully that should work.

Good luck 🙂

NB: ensure you ctrl + click and "erase deleted messages" on your trash folder in mail prior to exiting.

you are welcome.
Incidentally, are you using your "bounce" facility regularly?
As I keep bouncing loads of junk and get very little these days, about
1 a day is about it.
by customising your toolbar, you can drag the bounce into it. The nice thing about bouncing is that the junk mail sending computer "thinks" your email does not exist at all, thus will eventually cease to send junk.

Glad you were able to sort your mail problem out. 🙂

bouncing is a stupid policy that wastes bandwidth. usually the offending spammer uses a fake reply-to address that belongs to some innocent in order to avoid some spamming filters.
i can remember when some television station near me kept sending me virus-infected emails that were bounced by their virus checking program because the abuser used my address. when you bounce it has no effect on how people send you email.
if you want to know who sends you junk you need to look in the mail header (and block certain IPs.)
if you want to make sure that aa sender doesn't know if their mail was effective then make sure that your email client doesn't download any images in mail because some of them are web bugs designed for that purpose. and don't allow your client to sign mail receipts automatically.
there's no need to be unkind to others by bouncing because that is spamming too.
-marc

sorry to tell you, but I shall continue to bounce. If a person sends spam, then I WILL bounce.
And talking about unkind, it is you who is unkind by interfering.
Have a nice life.