[derefr]

Filters apply on a dumb level: do this if exactly this address, etc. I hope this would apply on a higher, "do what I mean" level: attempt to figure out if each new From address is actually the same person or organization as one you've already blocked, and, if so, add it to the "contact" of the blocked party so that it's blocked too.

[aiiane]

The failure case for that logic is pretty bad.

[derefr]

Depends on how they expose the UI for it. You could have a bin at the bottom of your inbox labelled "messages from recently auto-blocked senders"—with the messages still technically in the Spam folder and liable to be erased after 30 days, but exposed so you don't have to hunt through your "confirmed spam" to see them.

Throw in a little tweak to detect if you go on vacation (e.g. no messages opened in the last week, etc.) and pause the "decay" of messages in the spam folder until you get back, and it'd be just as safe as the system we have now.