If I "Junk" a Spoofed Email, Will Outlook Filter Out Genuine Emails?

I got an email from a relative of mine that I could see right away was not from him. I called him up to say that his account was hacked, but he says it was hacked a while ago and the guy got his email address and contacts, and now - after he regained control of the account - the hacker uses those to send emails to his contacts with a fake return address. IOW the guy sends emails to everyone on my relative’s contact list pretending to be [Joe.Blow@gmail.com] and with the “From” field showing that email address, when in reality the email is coming from a different email address altogether. (Those emails do not show up in his “Sent” folder.)

My question is if I can tell Outlook to send all emails from this sender to go straight to “junk”, or if that will send all emails that actually do come from [Joe.Blow@gmail.com] to the junk folder too?

Essentially ISTM that the question is: is the fake “From” field just something that’s coded to appear that way, but the Outlook “knows” what the real sending address is, or is it actually tricking the program into thinking that’s the real sender?

AFAIK if you make a rule that sends the email to junk based on the “from” address then it will follow that your friend’s email will go there too.

Outlook MIGHT check for domain keys from Google, a signature that Outlook knows that Google sends. But it might be lazy or not configured to do that.

What I would do is make a rule that if email comes from joe.blow@gmail.com and header does not contain smtp.gmail.com then send it to trash. I am fairly certain one would not be able to send spoofed email through Gmail’s smtp server in any fashion, and lack of that smtp server in the route info would verify the spoof.