Reasons to Use the Mailbox Alert Flag?

If you have a mailbox or have ever been near one, you may have noticed that there is a little flag attached to it. Sometimes the flag is orange, but most times it is red. This flag is known as a mailbox alert flag or a carrier signal flag. This flag signals the post carrier that the mailbox has mail that the house owner or customer wants to be delivered. Therefore they should pick it up.

A mailbox alert flag is not present on all mailboxes as you can choose to have a mailbox that only has incoming mail, but some people prefer sending their mail through their mailbox as well. Thus, it is quite useful as well. 

Clearly, a mailbox alert flag is pretty important to some people. Read ahead to find out why you should use one too.

Why do mailboxes have a flag?

Why do mailboxes have a flag

Most mailboxes have a flag on them as a mailbox’s purpose is to both receive and send mail. When the flag is down, it signals to the mail carrier that you do not have any new mail that needs to be delivered. When the flag is up, it informs the mail carriers that you have outgoing mail. A raised flag will also signal the postal carriers to make a stop at your house even if you have no mail to be delivered as there is mail that needs to be sent out. 

Some mailboxes feature a metal clip located on the inside of the door. This clip is where the outgoing mail is placed. Once the mail carriers have picked up your outgoing mail, they will push down the flag. Some flags have a self-lowering feature and will go down without you having to touch them. There also some devices that notify you when there is mail placed in your mailbox

If you do not have a flag on your mailbox, you lose out on the chance to send mail without receiving it. Mailboxes without flags are not visited unless mail is to be delivered. Therefore, if you have to send out mail and do not have a flag, you are out of luck because the postal carrier will not open your mailbox till they have mail to deliver to you. Not having a mailbox alert flag thus, severely limits the services that a mailbox has to offer, as you are only limited to incoming mail.

USPS requirements for a mailbox alert flag

USPS requirements for a mailbox alert flag

Although USPS does not require you to have a mailbox alert flag, if you do, then there are some requirements you have to fulfill and some guidelines that you have to follow. 

The USPS asks that the mailbox alert flag be mounted on the right side of your mailbox when it faces the mailbox from the front. Therefore, when a postal carrier arrives to deposit or pick up mail, the mailbox alert flag is on their right side. This guideline helps create uniformity and ensures that the mail is picked up from places where it needs to. 

Additionally, the USPS asks that the homeowners ensure that the flag is neither too heavy nor too flimsy as it may create problems in its function. A mailbox alert flag should be light enough so that it does not require more than two pounds of force. However, it should not be so light that it does not retain its upright position until the mail is collected from it. Some mailboxes also feature a self-lowering flag system that automatically goes down when the door to the mailbox is opened. In such cases, the mail carrier does not have to touch the flag at all. 

USPS also details the materials that the flag should be constructed from. You can only have mailbox alert flags that are made from plastic or metal. Wood is not advised. Additionally, it should function properly no matter the material and must be durable enough to be used at least 7,500 times.

Color and design of the mailbox alert flag

Color and design of the mailbox alert flag

Contrary to popular belief, a mailbox alert flag does not have to be red. It can be of any color other than white, green, brown, blue, or yellow. However, you may or may not use these colors if it contrasts well with your mailbox. Although USPS prefers a fluorescent orange color, the color of the mailbox and the flag mostly depends on you.

The design that USPS prefers for the mailbox alert flag includes a flash that is four square inches at least. This size allows the flag to be seen from a distance. Hence, it makes it easier for the postal service to see it when they are delivering and picking up mail. Additionally, the flag should not have any sharp edges, which could hurt the users. 

Some Myths regarding mailbox alert flags

A mailbox alert flag has a pretty simple use as it signals the mail carriers that there is mail that needs to be collected. However, there are some common misconceptions that may hinder you from using it fully to your advantage. 

Firstly, some people believe that mailbox alert flags are designed only for outgoing mail. That is not true, but it depends on your postal carrier. Often, they would also raise the mailbox alert flag so that the residents would know that they have received mail. This helped the homeowners not make unnecessary trips to their mailboxes. 

Secondly, USPS does not require you to have a mailbox alert flag and whether or not you have one depends on the kind of service you have opted for. There are two primary classifications of mailboxes, limited, and full service. One is the limited-service that only accepts incoming mail. The full-service accepts both kinds and requires you to have a mailbox alert flag.

The third myth is that a mailbox alert flag can be mounted anywhere on the mailbox. These carrier flags have to have a specific placement which is on the right side of the mailbox when you view it from the front.

Another myth is that having a stiff carrier flag is better than having one that is loose. However, according to the USPS requirements, your flag should not require more than 2 pounds of force to lower. Therefore having a flag that is too stiff is a disadvantage. Your flag should not be loose either. If it is, it may fall down, and the mail courier won’t know that you have outgoing mail.

The best Mailbox Alert Flags 

The best Mailbox Alert Flags

Due to the USPS requirements, you must have a high-quality mailbox alert flag. Here are some of the best ones available on the market.

Mail Tattle-Tail Mail Alert Flag

The mail tattle is a mailbox alert flag that alerts you when mail has arrived and alerts the mail courier when mail si to be delivered. It is made using aluminum and has stainless steel hardware that makes it durable and able to withstand harsh climates. Additionally, this alert flag is powder coat painted yellow, and if you have a darker colored mailbox, then it will stand out, and there is no chance that the mail courier will miss it. 

Universal Peel and Stick Mailbox Flag

This universal peel and stick mailbox alert flag are the most convenient of all mailbox flags. It is incredibly easy to use as all you have to do is peel off the bottom and stick it to your mailbox. The flag itself is made using rust-proof material, that is powder-coated with a metal material. Furthermore, this flag sticks safely and securely to mailboxes made from any material provided that it is smooth and not gritty or flakey. The tape used in this flag is outdoor-rated and can withstand harsh conditions. 

Post Alert Mail Slide

The post alert mail slide is unconventional. Unlike other mailbox alert flags, it simply slides out and does not have that traditional flag shape. Furthermore, it slides in and out and not up and down as you would normally see. Nevertheless, this mailbox alert flag is simple to use, and it also makes the mail pickup process go by much smoother. It also complies with all the postal regulations provided that you install it correctly. Furthermore, this mailbox alert flag is also easily integrated into brick, stone, and traditional mail pickup boxes. 

Rooster mailbox flag

If you want to add a bit of personality to your mailbox, this rooster mailbox flag can help do that. This particular mailbox alert flag is made using aluminum and is further powder coated for durability. Due to this coating, it can withstand high temperatures and other weather as well. It is 9 inches tall, and the red paint ensures that it can be seen from a distance. 


A mailbox alert flag is a nifty addition to your mailbox that can make it so much more useful. Most people are unaware of how to use a mailbox alert flag and the reason why you should use one. This article details that a mailbox alert flag allows you to alert the courier that there is mail in the mailbox that needs to be sent out. Using the same flag, the mail courier can also inform you that you have incoming mail. Therefore it acts as a way of communication. It also helps save you multiple trips to the mailbox.

Thus, if you have the full mail service, be sure to add a mailbox alert flag for both; your and the mail courier’s ease.