I have a folder on my mail server called “Dead”. If I move an email to that folder then all subsequent emails to the same address as the first one go into “Dead/Match”. It’s driven by procmail and a script.

When used with one-off email addresses you get a behavior that’s like unsubscribing, but without having to trust any “unsubscribe” links or processes, and also without having to edit any config files (it’s all driven from iOS Mail.)

1/ book your hotel using the email address $RANDOM@yourdomain

2/ receive booking conformation and enjoy holiday

3/ when you eventually get marketing spam, file it in Dead and never be bothered again.