Hi,
Do you mean junkmail? here's what's in the FAQ...
How to set spamassassin for automatically deleting junkmail.
You can change the "days" that spamassassin sets to automatically delete junkmail, to do this just type at command line...
db configuration setprop spamassassin MessageRetentionTime 60Where 60 is the value you want, then do...
signal-event email-update