I have a friend whose email contributions from his work email address aren't being delivered to my hotmail address, nor my wife's hotmail address.  His emails neither appear in our inboxes, our junk folders, nor (though I can't imagine why they would be) our deleted messages folders.  I know that his emails are being sent from his domain mailserver because we are receiving copies of his emails in the content of emails being sent by other participants in the same email threads using "Reply All".  So not only are his messages definitely being delivered to everyone else on the thread who aren't using a hotmail account like my wife and I (most of the other addresses in the email threads are gmail accounts though some are unrelated work accounts), but his email client does appear to have a valid record of our addresses as "Reply All"s to his messages are reaching our hotmail accounts without issues.  We first noticed this about two weeks ago, and since then we've experienced it with 4 or 5 distinct email threads (with distinct participant addresses) as well as experimented with targeted emails from his account to just either one of us - we have yet to receive an email from him in any capacity (inbox, junk, etc.)