You can process the Spam as you see fit. It rewrites the headers of the email so you can do things like rewrite the subject line.
example:
You could convert an email subject line like:
"Original Subject" to
"Possible Spam - Original Subject"
You can setup a filter to delete emails that match a certain header criteria.
You can setup thunderbird/etc to move emails tagged as junk to the junk folder for processing later.
There are many options and you would be the one who decides if the email is automatically deleted or saved for later.
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