If someone emails from different domains like that, then they've missed one of the biggest security lessons in how to use the internet: only trust domains that you already know well and/or can verify. If you get an email from YourBank.kp or YourBankOfficialReallyIPromiseBro.com then don't trust it.
The burden of proof lies with the sender to convince you they are who they say they are, by providing verifiable info and not using a domain you have to go whois.
I think PayPal sends emails from PayPalMail.com or something like that, so when a friend asked me if it was real, I said probably not, but when I investigated it further I found the morons from PayPal did actually (sometimes?) email from another domain. It makes sense however that a company like PayPal, so closely connected to psychotic conman Musk, would do something that idiotic.