I use a catch-all email address and then use a unique email for each site. I also add a string and auto delete all mail without it (to not get random spam). IE

I use a catch-all email address and then use a unique email for each site. I also add a string and auto delete all mail without it (to not get random spam). IE ycombinator+my_string@domain.com. If I get spam I add the mail alias to /dev/null. Voilà, instantly aware of who sells data and bulletproof blocking.