Your email is scanned before it arrives at your inbox, the subject of email we identify as spam is marked with SPAM ***.
You can automate clearing your inbox of these spam emails a rule to your email program to send emails marked SPAM *** to your preferred folder, be it junk or trash. How this is done will vary across email programs.

Why don't we simply delete spam emails? We aim to provide maximum flexibility to our users by giving you the option to decide the fate of spam emails.