What is the date of an email if it has been stuck in the outbox for longer?

I sent an e-mail with an attachment and was apparently hectic, at least overlooked the fact that it wasn't ready when I packed the laptop. Now I'm wondering what date the email will be. The output shows when I clicked submit. But is this also transmitted?

The date from when it was actually sent out and is no longer in the outbox.

So my experience.

As a rule, the outbox is like a clipboard.

The date when the email was sent.