While the Exchange email filter identifies the majority of spam, phishing, and other email threats, a small number of wanted emails end up in one’s Junk email folder. By modifying a few settings in Outlook, you can “train” the filter to direct legitimate email into your inbox and block unwanted email.
In Outlook,
Right click on any email message, select junk and then select junk mail options. Here you can add/edit/remove safe senders and blocked senders as well as choose to trust all email from your contacts list and email addresses that you have sent to.