Open your mailbox.
Select Options on the top right hand side > Mail Options > Filters > Add Filter.
Select Filters.
Click "Add Filter".
In the top row, labeled From Header, select contains from the pull down menu. Enter the address in the text box next to the pull down menu.
Example: You can either give a specific email address or use @rainbowplantlife.com or *rainbowplantlife.com to whitelist the domain.
Move down to the bottom where there is the option Move the message to. Select Inbox from the drop-down menu.
Select the Add Filter button once again.