A rule is a set of criteria and automatic actions that will be
applied to new messages as they arrive in your mailbox. Your
email program will first check to see if a new message meets the
conditions you have specified, then it will perform an action
such as move it to a folder. Rules can be used to manage your
email by automatically organizing messages into folders as they
arrive. To set up a new rule: - Choose Mail, Preferences and
click Rules. - Click Add Rule and type a descriptive name for
the rule. - Set the conditions necessary for the rule to apply
to a message. - Choose actions to perform on messages that meet
the conditions. To specify multiple criteria and actions, click
the Add (+) button. If you have multiple rules, they’re applied
in the order in which they appear in the Rules list. Drag a rule
in the list to change its order. The rule will be applied to all
future messages you receive. To apply the rule to messages
already in your mailbox, first select them (you can use the
Command + A shortcut