What happens to the temporary email after it expires?

Question

Information Security

There are services that provide a temporary email.
What happens to the temporary email after it expires?
Are all emails sent to it deleted?
And is it safe to register on various sites using a temporary email?
Since after the expiration of the period you will no longer have access to the temporary box, and the incoming letters remain in it. (do they stay?)
Can the owners of the service see them?

Answer 1

What happens to the temporary email after it expires?

unknown

Are all emails sent to it deleted?

unknown

And is it safe to register on various sites using a temporary email?

"safe" is too general a term

Can the owners of the service view them?

unknown

Answer 2

What happens to the temporary email after it expires?

What happens is what is provided for this service. What - only the admin knows, but he will not tell you, even if you ask (and what he says may not be true at all)
May be. Or maybe not. Only the admin knows this, but.. see the answer above :)
What is "safe" in this context?
May be. Or maybe not. Only the admin knows this... well, you get the idea :)
You can't be 100% sure about anything that happens on a site that you don't have physical access to at any time. Everything that the service claims can be true . Or maybe she doesn't have to be. Remember how the Pindos in the movies say "Whatever you say can be used against you." Here is exactly the same situation.