Authorities knew the tweets were not really coming from Donald Trump because the hacker Failed to Capitalize Every other Word and he neglected to use dozens of exclamation points.
Dutch authorities: Trump's Twitter account was hacked by man who guessed 'maga2020!' password
It took the hacker only five tries to guess the correct password and he was kind enough to tell Donald Trump's team to activate two-factor authentication afterward.
https://www.huffpost.com/entry/dutch...5b610200988b2a