The MailGuard Mailbox (Green) Weatherproof, Rust, Fade and Peel Resistant Incoming mail opening (behind the upper door) is 10" wide x 2" high - large enough for FedEx envelopes, check boxes, video tapes, etc. Outgoing Mail - sits on a shelf inside the unlocked upper door. The bottom section of the mailbox, where incoming mail is stored is 6" deep. The lower, locked door is 8" wide x 6" high. Mailbox dimensions: 24 1/2"H x 12"W x 18"D