I own a domain, for example xyz.com, which means I can create whatever email I want, like lemmy@xyz.com.

The mail server I set up forwards all emails to one inbox. Which means I still get an email if you send it to reddit@xyz.com or whatever@xyz.com and so on, you get the idea.

So when I sign up for an account I don't use a general email (except for banking stuff, taxes, etc.). If I sign up for Facebook (good riddance) I'd use facebook@xyz.com. That way I also know when I suddenly get a lot of spam who lost my email or sold it off :)