Missing Emails since yesterday

Scan to email on my copier to outlook.com used to work 2 days ago. Now it sometimes goes to my Junk folder or it does not show up at all. This is randomly effecting all users in the organization. Sometimes it shows in the inbox, junk folder, or disappears. I have instructed the users to add the sender's address as a contact, as well as the sender's domain and email address to the safe list but the problem still exist. I thought adding to the safe list is like white listing and guarantees a successful delivery regardless of content. Can someone verify where the email is going and how do I prevent this? The email contains only the subject and scan document. Again, it's been working fine since we switched our mail to outlook.com until 2 days ago.