We have a single company whose emails are in Office 365 and when they email any Shaw email address it goes to the junk folder. When I email the same Shaw address from my Office 365 email (not associated with the company) it goes through just fine. We are setup exactly the same way, the only difference being email address/domain name. I've checked the problem domain against all public blacklists and they aren't on any. 

Is there a way for us to determine why the emails are getting sent to junk in the Shaw email system?