Where does the official approval letter come from after the Australian visa is signed?

The approval letter was sent directly to you by the Immigration Bureau, and it was not downloaded. There are two forms of visa letter: one is a file format with the logo of immigration bureau, and the other is an email directly saying that the visa has been passed.

Usually it's dear xxx. I'm glad to inform you that the visa application has passed, and then I'll tell you something like Grant Number. If you find that you have signed the letter but haven't received it, you should contact the embassy. It seems that if the letter is signed, it can't be made up. But he should be able to find your funding number. You can download your own Visa Elite Check in VEVO system and use it when you enter the country.