email w/ attachment received from specific user will NOT sync to desktop Outlook or iPhone

I primarily use Outlook on my desktop and want to keep it that way.  I do a lot of work with a company and send and receive emails from several users all day long with no problems.  All but one person can send me an email with attachment without any issues.  If this one specific person sends an email with attachment, it will get to my outlook.com web interface but WILL NOT sync up with Outlook on my desktop or iPhone email.  This is one user, only when there's an attachment.  It works the same way if she forwards a message with attachment or creates a new email with attachment.  The same user can send me non-attachment emails just fine all day long.

I have worked with their corporate email help desk.  They looked through several messages and the headers looked normal to them.

I normally don't use outlook.com on the web because I have Outlook on my desktop, but have to remember to check the web daily in case there's something hiding there.  Fortunately I can work with these strange emails without issue from outlook.com but of course I prefer to have all my email in one place.

Any help would be appreciated.

Thanks,

Jeremy