"Anonymous" with respect to the provider doesn't equate to "anonymous" with respect to the privacy invading culture of the internet.

About the only way to keep an email address truly "anonymous" over time is to not use it for anything significant or important.

For example, friends and family will invariably store your address on their phone along with your name, address and phone number.

One roque app on their phone is all it takes to blow your cover.

Also, someone will eventually send you an email using a "free" privacy invading provider that includes all your PII. Busted again.