Then start setting up unique email addresses for each service, e.g. [email protected] . The "abcd" part should be random for each service so it's impossible to guess your other email addresses.

I also use yearly throwaway addresses, e.g. [email protected], for when I need an email address without having the means to create a new alias first. (I then change that later.)

Should spam starting to appear, you'll know exactly which service "got hacked" (i.e. sold your email address) and can just disable that alias and create one with different random letters. Also when deleting an account somewhere, just also delete the alias and you won't get any mails about signing up again.

It takes a bit of discipline but it gives you lots of control over your inbox.