In Mac Mail, email filters are known as rules. You can use these rules to automatically move certain email messages to a mailbox (folder) in Mac Mail.

1. In your Mac Mail program, click on the Mail menu and select Preferences.
2. In the Preferences screen, click on Rules.
3. Click on the Add Rule button which will open a dialog box for you to input the settings for your rule:
   Description: A name for your new rule (can be anything you want)
   If Any/All: Choose whether the rule should apply if any (1 ore more) or all of the conditions are met
   Conditions: Select a condition you want for your rule. Add additional conditions as needed. For example, you might filter your email so that if the subject line contains the word "receipt" it will be moved to a Receipt mailbox.
   Perform the following actions: Choose the actions to be performed for this rule
4. Click the OK button to save your new rule.