An email somehow finds its way into your Junk folder, and this should not be!
Follow this process to add the sender to your Safe Senders list. This change will reflect in your Office 365 account online.
1. Right-click on the email.
2. Hover over 'Junk'.
3. Select 'Never Block Sender'.
4. A rule will be created for your account so that emails from the specified sender will never be blocked.