That's actually the opposite to what people do here in Sweden. Because once that letter goes out to everyone the new contract is already signed and the current employment is already terminated.

We usually have 1-3 months resignation period, so there is no resignation letter. The closest we have is a goodbye letter that goes out to all your co-workers. And this letter reminds me most of those.

The actual resignation is done in person with your manager. Of course you could do it over e-mail but I'd be willing to bet 99.99 out of 100 times your manager would schedule a 1-on-1 meeting with you if they received such a resignation.