Imagine someone visiting your blog who wants to e-mail you can burn some CPU cycles to "earn" an address that hasn't been given out to anybody else, e.g. user+TOKEN@example.com, where it is algorithmically-unlikely for them to be able to guess a different TOKEN that will work. Then if abuse occurs, you can just retire that one address. (In a non-interactive context, like a paper ad, you could just generate one yourself.)
Naturally, this would be best with an e-mail client that is aware of the scheme, and with a mail-service that has some API for generating new addresses, such as if you want to cold e-mail somebody and use a new from/return address.
Some years ago I had the fanciful idea of doing it with a phone-app, where it manages creating new addresses as-needed, disabling them, and keeping notes about who you gave them to.