I do something else to avoid such things, which is I use a different email address for each correspondent. If I accidentally sign up for spam, I can just remove

I do something else to avoid such things, which is I use a different email address for each correspondent. If I accidentally sign up for spam, I can just remove that address from the /etc/aliases file and then they won't be able to send any more spam to my email. (I have also configured my email so that it only supports aliases, and not actual user names.)