This is an upgrade suggestion for the current default 30 delation time for spam emails. The least upgrade that is needed is the ability to specify retention times other than 30 days, specifically less than 30 days for all mail directed to the spam inbox.

The better upgrade would be the ability to specify retention by sender address; even down to 0 which would mean that subsequent emails from that sender would be deleted on receipt. (Since there are email senders that don't respect the unsubscribe function, they tend to accumulate as spam for a month which just makes managing email more difficult as it's harder to sort through all the debris in spam to find items of potential interest).