Dodgy emails - 1/2 of my alias email address used to send me emails?

Eg, my email address is: ***g@icloud.com. But I am getting emails addressed to ***7@icloud.com which isn’t my address so how are they getting through to me?

When I go into the Privacy box it goes on about even if I unsubscribe the site may still sell my info. Shall I just delete this email address. And if I do, will I be able to create another alias as I already have 3? Thank you.

[Edited by Moderator]