What's the best legal alternative to mailbox distribution?

Putting unstamped cards into residential mailboxes is illegal, because the mailbox is reserved for USPS mail. The closest legal equivalent is Every Door Direct Mail (EDDM), a USPS program built for exactly this kind of neighborhood saturation.

• Choose carrier routes by zip code, and the post office delivers your piece to every address on that route.
• No mailing list required, you target geography instead of individual names.
• Postage runs around $0.20 per piece, on top of printing.
• EDDM has size and format rules, so design your piece to the accepted dimensions before printing.

It reaches the same doors as illegal mailbox stuffing, but with full USPS backing and tracking.