I love using iCloud's Hide My Email feature to create a unique email for every signup form or random person you contact. You can also use a Custom Email Domain

I love using iCloud's Hide My Email feature to create a unique email for every signup form or random person you contact. You can also use a Custom Email Domain with iCloud so I can imagine this feature might be usable outside the Apple ecosystem. Overall I find this system very easy to use. If you are outside the Apple system you can use the web interface for managing your email addresses, but it's missing some small features: for example, you can't see when's the last time an email address has been used.