How do I search Bulk mail for an address that may be getting block inadvertently?

My Trash collector claimes to have emailed me my bill but it never arrived in my In Box. They think it may have been stopped by a spam blocker. How can I enter thier address as NOT SPAM directly. Or how can I search the 1000+ blocked mails for thier letter?|||easy dude! at the top-left, there should be a box, type in their email address, once it's been found, mark as not spam