About 90% of my email actually is being forwarded to the onmicrosoft.com account. For no apparent reason, some of the email is not forwarded and instead winds up in the live.com/outlook.com inbox.  I have had emails from one sender forwarded, while another email from that sender was not.  

Given that most of my mail is correctly forwarded, there obviously is not a problem with the forwarding setup.  I have confirmed that the emails that are not forwarded never reached the firewall of the onmicrosoft.com server, which both confirms that they were not forwarded and is consistent with those emails being in the live.com/outlook.com inbox, where they should not be if they were forwarded.  

So, why does live.com/outlook.com not forward all email when the account is properly set up to forward all email?  

Dan