How to Whitelist a Domain in Mac OS X Mail App

The spam filter in Apple's Mail app is effective at catching junk mail, while still allowing mail from known senders to reach your inbox. However, this applies to individual senders (i.e., mail from a specific user's email address, like user@example.com) and those in your Contacts; it does not automatically allow through mail from an entire domain, such as all addressed that ends in example.com.

You can set the Mac Mail app to "whitelist" a domain so that it allows through mail from all addresses from that specified domain. To do so, you need to set up a rule in the Mail preferences.

To whitelist all email from a specific domain in the Mail app in Mac OS X or macOS:

1. In the Mac OS X Mail top menu, click Mail > Preferences.
2. Click the Rules tab.
3. Click Add Rule.
4. Type a name in the Description field, such as "Whitelist: example.com," to identify the new rule.
5. For the conditions, set the first dropdown menu item to any, so that it reads: If any of the following conditions are met.
6. In the next two dropdown menus, select From in the first, and Ends with for the second.
7. In the text field following Ends with, enter the domain's name that you want to whitelist. Include the ampersand "@" before the domain name to make the filter specific—for example, to whitelist all mail from the example.com domain, but not mail that might come from one of its subdomains (such as @subdomain.example.com), type "@example.com" into the field.
8. Click the plus sign next to the last condition to add another domain with the same criteria if you want to whitelist more domains.
9. In the Perform the following actions section, set the three dropdown items to: Move Message, to the mailbox: Inbox (or specify a different target folder of your choosing).

The order of the rules you have set matters, and Mail executes them one after the other, moving down the list. This point is important to consider because some messages may satisfy the criteria established in more than one rule you've created, so you'll want to consider the logical order in which you want each rule to be applied to incoming messages.

To ensure that the rule you've just created that whitelists a domain is executed before others that might also apply the same message, click and drag that rule to the top, or near the top, of the rules list.

For example, if you have a filter that color-codes certain messages based on keywords in the subject, move your domain whitelist rule above that labeling rule.

Junk mail filtering is active by default in the Mail app. You can find these settings by following these steps:

1. In the Mac OS X Mail top menu, click Mail > Preferences.
2. Click the Junk Mail tab.

You can tailor your junk mail filtering settings, including specifying where junk mail should go and defining exemptions for junk mail filtering.