Strange considering how venerated Sony was by American business leaders. Steve Jobs even tried to convince Apple to adopt corporate uniforms like Sony's.
I ran into this issue several years ago. After complaining, MS allowed me to send email to MS properties (hotmail, live.com), but continued to block my email to their Office 365 clients.
I now use AWS SES to handle mail delivery. It's free for up to 200 daily messages which is fine for me.
I've been using https://domains.google/ for years. $12/year/domain. Email forwarding is included. I don't even know if they charge extra for anything else.