A rule is an action that Outlook 2016 or Outlook 2013 for Windows runs automatically on incoming or outgoing messages. You choose what triggers the rule as well as the actions the rule takes. For example, you can create a rule to move all messages from your manager to a folder or to delete all messages with "Buy now!" in the subject.
How rules help you manage email messages
By using rules, you can reduce manual and repetitive actions needed to manage your email messages. When you turn on rules, they run continuously and automatically.
Rules generally fall into one of two categories—organization or notification. You can use the Rules Wizard to help you design rules to manage your messages.
The Rules Wizard includes templates for the most frequently used rules.
These rules help you not only to file messages, but also to follow-up with messages. You can create a rule for messages from a specific sender. So you could set a rule, for example, that messages received from Keri Mills with the word "sales" in the Subject box are to be flagged for follow-up, categorized as Sales, and moved to a folder named Keri’s Sales.
Stay Up to Date
These rules notify you—based on choices you make—when you receive a particular message. You can create a rule, for example, that automatically sends a message to a mobile device when you receive a message from a family member.
Start from a blank rule
These are rules that you can create and customize without a rule template.
Read this step-by-step article from Microsoft on managing your rules.