Rules only run when the message is received by Entourage. So, in this case,
the rule would only function as you are expecting if the message was
received over one day after being sent. Also, if the message was not
classified as junk by a rule before this rule (or the Junk Mail Filter), it
wouldn't be moved, because Entourage wouldn't know if the message is or is
not junk.
More efficient would be to download a copy of Paul Berkowitz's "Delete Junk
Folder" script and run it daily. You can get a free copy from
ScriptBuilders @ MacScripter.net:
<
http://www.scriptbuilders.net/?search=delete+junk+folder>
When you have downloaded the script and read the instructions, move it to
the Entourage Script Menu Items folder (HD/Users/<Your
User>/Documents/Microsoft User Data/Entourage Script Menu Items/). Then, go
to Tools -> Schedules, and click "New". Name the new schedule "Delete Junk
Folder". Make it look like this:
WHEN Repeating Schedule Every 1 Days
ACTION Run AppleScript Delete Junk Folder X
Check "Enabled" and click OK. Each day, from now on, the Junk folder will
be cleaned out. Of course, you can adjust the "WHEN" section to your liking
if that's too frequent. If you want to, you can even do this manually by
going to the Script menu (to the right of help) and then choosing Delete
Junk Folder X.