YT, 'apparently' it is not difficult to spoof the from address in an email. Don't ask me how though.
Your other option would be to whitelist your incoming messages. i.e. Only accept messages from those in your address book. I would imagine MS has this option (but I don't know how this application works)
To use Apple Mail, you do not need to change your email addresses or domain name. Open Mail, go to preferences and create (a) new account. Enter your email address and your password. Bob's your Uncle.