How to whitelist an email address in Gmail

On the right, click on the cog wheel and hit Settings.

Click on Filters and Blocked Addresses.

Click on Create a new filter.

In the From field, enter the email address.
Then at the bottom, click Create filter with this search »

In the next screen, check Never send it to Spam.
Then at the bottom click Create filter.

Go to Inbox on the left to get back to your emails.

You can also add the email to your contacts to keep them from going into Spam.