Can USPS carriers remove unauthorized flyers from mailboxes?

Yes. Letter carriers are instructed to treat unstamped items in a mailbox as unauthorized use of the box, and they can act on it. Because the mailbox is federal territory, anything placed there without postage is fair game for removal and reporting.

• Carriers can remove the material during their route.
• They can file a report with the local postmaster identifying the sender if the piece is traceable.
• The postmaster can then follow up with a warning or pursue penalties for repeat activity.

Rather than risk having your marketing pulled and reported, mail it properly. A USPS-compliant mailed flyer reaches the same doors and stays in the box legally.