You can find several discussions of this practice online, including people commenting that they receive email for previous holders of those ids.

The commenter above may have never deleted the alias to release it for reuse.

Reusing email addresses is pretty universally considered terrible practice. So you may want to discuss it with your friends there.

I will. But for everyone on this site, the real answer is to own your own domain and use that. Then your email service is just a commodity.