That's not blocking, then. You're just accepting the email and not doing anything with it. It's usually called "blackholing". It's less nice to the senders for obvious reasons.
It's been called blocking for decades, but sure, we can call it whatever you like. From my point of view, it's blocking because it blocks the emails from reaching me.
There's also a perspective of a sender, and if you return "250 Ok/Queued" from your server, you didn't block anything, regardless of what you do with the email afterwards.
