Not sure if anyone has ever heard of this site before - But it allows you to create completely free and anonymous emails for any site.
Essentially, you select a username when you sign up. This creates you a subdomain of anonaddy.com
When signing up to any website or service, you can then create a random email that will then be automatically created and added into your anonaddy dashboard.
Personally, I use the service for literally everything. If I were to sign up for PayPal, I could use email@example.com.
Any emails that the address receives are automatically forwarded onto my personal account. I can also turn off the address, or edit the destination at any time.
It’s literally amazing - Open source - And Free!
They do offer a premium account that unlocks custom domains too.