What Is the Purpose of the Mailbox Flag?

By Sumei FitzGerald - Updated May 31, 2017
US post mail letter box with red flag

The flag on the side of your mailbox is meant to be used by you and your postal delivery person: It is meant to signal that something is inside that needs picking up by either you or your carrier.

Not all mailboxes have flags and not all postal carriers pay attention to a raised mailbox flag. Postal carriers rarely raise flags themselves after they’ve delivered your mail today but thieves may take notice of the upright flag you’ve put up: A raised flag signals an opportunity for a crime known as “check-washing.”

The Advent of the Flag

The signal flag on the side of mailboxes was instituted in 1915 by Roy J. Joroleman, according to the Smithsonian’s Postal Museum. Postal carriers were to raise the flag so residents would know when they’d received mail. Postal customers also raised the signal flag so that the postal carriers would stop to pick up outgoing mail even if mail wasn't being delivered to that mailbox that day.

Flag-less Mailboxes

Not all mailboxes have flags. The United States Postal Service (USPS) allows postal customers to use locked mailboxes as long as the opening is large enough for their normal volume of mail. In this case, the postal carrier cannot access the box to pick up outgoing mail. USPS regulations also don’t apply to wall-mounted mailboxes or mail slots.

The Bobi mailbox is a curb-side mailbox without a flag. It was developed in a California community to allow for the passage of residents in wheelchairs. It is vertical rather than tunnel-shaped and has a locking feature.

Official Raised Flag Policy

In 2007, WBLT Channel Three investigators looked into the official postal flag policy when residents of Ridgeland, Mississippi, complained that postal carriers ignored raised flags signaling their outgoing mail.

Ridgeland resident Martha Harrell, after chasing down the postal truck, was told that carriers weren’t required to stop at mailboxes if no mail was being delivered to them that day. But the postal service said curb mailboxes should be checked for outgoing mail regularly and the postmaster called the postal carrier’s view an “unfortunate oversight.”

A Beacon for Thieves

In 2009, Ventura County reporter Kit Stolz experienced a serious case of identity theft after leaving paid bills in the mailbox and raising the mailbox flag.

The reporter placed two bill payments in the mailbox and noticed that the following day, the mailbox flag was still up but the bill payments were gone. The next business day, two checks from Stolz’s bank account had been written for large amounts at department stores and by the following day; seven more checks had been written.

Stolz’s bank representative explained that thieves steal outgoing mail and “wash” checks to appropriate them for their own use.

“Check-washing” is the chemical erasing of ink on checks, says the Identity Resource Center, funded by the U.S. Department of Justice (DOJ). Once the erasing occurs, thieves can write in payees and amounts as they wish.

Ventura County detective Eric Buschow told Stolz that the red flag is “like a beacon for thieves,” who use the information on checks they find to make up checks of their own.

The Death of Mail

The mailbox flag might be a moot issue today. In 2009, Washington, D.C., reporter Brigid Schulte found that 200,000 mailboxes had disappeared from curbsides in the last two decades: Only 4,701 mailboxes remained in D.C., Northern Virginia and Maryland suburbs.

The USPS said that it has to remove “underperforming” mailboxes after conducting mail “density tests.” Technology has made “snail-mail” a relic in its own time.

About the Author

Sumei FitzGerald has been writing professionally since 2008 on health, nutrition, medicine and science topics. She has published work on doctors' websites such as Colon Cancer Resource, psychology sites such as Webpsykologen and environmental websites such as Supergreenme. She holds a Bachelor of Arts in sociology from the University of Connecticut where she also studied life sciences.

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