To make sure that any messages you receive from a specific person outside our domain pass through the spam filter, create an email filter using the Never send it to Spam option:
1. In Gmail, click Settings.
2. Select the Filters and blocked addresses.
3. In the Filters and blocked addresses window, click Create a new filter.
4. Enter the person's address in the From field, and then click Create a filter with this search.
5. Select Never send it to spam, and then click Create Filter.
* This filter will only apply to new emails. Previous messages will remain in their current location.