In this era where everyone sends messages and almost no one writes letters anymore, sending a physical letter has become all the more precious. And that’s why—whether it’s a first-time mailer or an experienced corporate mail carrier—often makes a mistake on a seemingly “trivial” action: affixing stamps.

You might have just bought a batch of discount stamps, planning to send out wedding invitations or business invitations, or perhaps you were attracted by the beautiful designs of the Forever or floral series and picked out several sets of Forever stamps. But if you get a cold “Return to Sender” sticker from USPS because you pasted it in the wrong place or the wrong way, that feeling… is truly enough to make you feel devastated.

Affixing stamps is far more complex than simply “sticking paper on a stamp.”
USPS’s high-speed sorting machines, orientation recognition systems, and fluorescent marker scanning all have strict regulations regarding the position and condition of stamps. The following five most common mistakes account for nearly 80% of returned mail.

If you are planning to mail invitations, holiday cards, or formal documents, be sure to avoid them.

Rule 1: Always remember the “Top-Right Rule.”

It sounds very simple, but it’s also the easiest thing to overlook.

Correct procedure:
The stamp (whether discount stamp or forever stamp) must be affixed to the designated area in the upper right corner of the front of the envelope.

Why is it so rigid?
Because the USPS automated sorting system (Facer-Canceler) will prioritize scanning this area in order to identify the fluorescent markings on the USPS stamp and complete the capping process.

Common errors include:

Place it in the top left corner (where the sender’s address is located).

Stick it on the back of an envelope or even use it as a sealing sticker (please do not!).

If the system cannot find the stamp, your letter will be considered “no postage” and will almost certainly be returned.

Rule 2: Never seal stamps with tape (No Tape Allowed)

This is a common misconception among many senders: “It’s to prevent the stamp from getting lost.”

But the reality is—

Adhesive tape is the “enemy” of USPS sorting machines.

The reflective material from transparent tape can interfere with the sorting system’s ability to identify the anti-counterfeiting features on stamps. Even worse, stamps sealed with tape cannot be cancelled, and the machine will interpret this as an attempt to reuse the stamps, thus deeming them invalid postage.

Correct handling method:

If the adhesive on the back of the stamp is not sticky enough (this is extremely rare), please apply a thin layer using a glue stick.
Do not use tape, double-sided tape, or packing tape, and never cover the entire stamp with film.

Our many forever stamps are all pressure-sensitive adhesive and do not require any additional treatment under normal circumstances.

Rule 3: Multiple stamps? Please keep them separate and do not overlap.

When the letter exceeds 1 ounce, you might post:

A forever stamp

Add an Additional Ounce fare ticket

Or use multiple discount stamps to reach the total amount.

Correct method:
Stamps can be placed side by side, in a row, or in a column, as long as each stamp can be seen completely.

Fatal mistake:
Overlapping stamps in an attempt to “save space.”

If the stamp is covered, the machine cannot read the denomination, and your letter will either be returned or the recipient will have to pay extra postage—neither of which is very respectable.

Rule 4: Uneven envelopes will trigger an additional charge (The Lumpy Envelope).

Wedding invitations and holiday cards are especially prone to mishaps.

For example:

Wax Seal

ribbon bow

Thick cardstock, rigid inner pages

These will all cause noticeable bulges on the surface of the envelope.

USPS standard mail must pass smoothly through high-speed roller sorters. If the envelope is too thick, too stiff, or has a bulge in any part, it is very likely that:

Machine stuck

This caused the machine to forcefully press down on the envelope.

The envelope was torn, and the contents were damaged.

Solution:

Purchasing a “Non-Machinable Surcharge” stamp typically costs
about $0.40 more than a regular forever stamp.

Don’t take any chances; letters with incorrect postage have a very high return rate.

Rule 5: The Hidden Costs of Square Envelopes

Square envelopes do look “high-end,” but USPS machines don’t like them.

The reason is very simple:

The machine cannot determine “which side is the top.”

Envelopes with uniform length and width cause the orientation determination system to “malfunction,” so all square letters are assumed to be non-machine-checked mail.

result:

An additional fee must be paid; a regular USPS stamp or forever stamp cannot be obtained on its own.

Want to save money?
Please choose a standard rectangular envelope, such as A7 or #10 size.

In conclusion: The seemingly small matter of affixing stamps can determine the success or failure of a mailing.

Sending a letter is a ritual and a way to convey care; however, whether it can be delivered smoothly often depends on these seemingly insignificant details.

If you are preparing to send wedding invitations, holiday cards, or business letters, be sure to remember the following:

Purchase high-quality discount stamps or forever stamps to avoid the risk of counterfeit products.

The stamp should always be affixed to the upper right corner and kept flat.

Do not overlap multiple stamps.

If the envelope is not flat, be sure to affix a “Non-Machinable” label.

Square envelopes always incur an extra charge; please prepare postage in advance.

Now that you’ve mastered the method, it’s time to pick out a set of stamps for your envelopes that will leave a lasting impression and save you a lot of money.