It turns out that the Searchable proper on the Contact field Do not allow bulk emails defaults to No, as you can see below:
This is a problem when you want to perform a search for Contacts who have this field set to Yes.
To change this setting, perform these steps:
1. Select Settings, Customization, Customize the System.
2. When the Default Solution is displayed, Navigate to Entities.
3. Then navigate and expand Contact.
4. Click on Fields.
5. Locate the field: Do not allow bulk emails.
6. Chang the Searchable setting to Yes.
7. On the Toolbar, click the Save and Close button.
8. Publish Contact (or All Customizations).
Now, when you are performing an Advanced Find on the Contact entity, you will be able to see the Do not allow bulk emails in the drop-down list.
We’ll talk more about how and why this is a useful feature tomorrow.