USPS First-Class Mail Letter (FCML) shipping for sellers

USPS First-Class Mail Letter (FCML) lets U.S. sellers ship eligible card and sticker orders in a standard paper envelope instead of a package.

Also known as plain white envelope (PWE) shipping, FCML can help lower shipping costs for both sellers and shoppers.

To use FCML, turn it on before your show starts. Once enabled, FCML automatically applies to eligible shipments during that show.

FCML works best for lightweight, low-value orders, but not every shipment qualifies. If an order becomes too heavy, too valuable, or too large, Whatnot automatically upgrades it to another shipping method before you ship.

In this guide:

• When FCML applies
• How much FCML costs
• Turn on First-Class Mail Letter shipping
  • Turn FCML on for future shows
  • Update FCML for a scheduled show
• FCML envelope requirements
• FCML shipping time and limited tracking
• Confirm drop-off for FCML shipments
• If your shipment doesn't qualify for FCML
• FAQs

When FCML applies

FCML works best for lightweight, lower-value shipments that can easily ship in a standard paper envelope.

FCML automatically applies to eligible shipments when all of the following are true.

Your items must:

• Be sold in the Trading Card Games, Sports Cards, or Stickers categories
• Be sold during a live show
• Not use a custom shipping profile or max bundle size

Your show must:

• Have FCML turned on before the show starts

The shipment must:

• Contain 5 or fewer items
• Weigh 3 oz or less total
• Have a total shipment value of $20 or less
• Ship to a buyer in the U.S. (domestic shipping only)

If a shipment no longer meets these requirements, Whatnot automatically upgrades it to USPS Ground Advantage or Priority Mail before you ship.

How much FCML costs

As of July 13, 2025, FCML label prices on Whatnot are:

*Note: FCML shipping costs include the USPS label price plus a small operational fee that supports features like Smart Bundling and Flat-Rate shipping. Whatnot partners with carriers to help provide competitive shipping rates to our customers. 

Turn on First-Class Mail Letter shipping

You must turn on FCML before your show starts.

Once enabled, FCML automatically applies to eligible shipments during that show.

Turn FCML on for future shows

You can enable FCML for future shows by updating your shipping settings in Seller Hub. 

Update FCML for a scheduled show

If you already scheduled a show, you can turn on FCML before the show starts. 

If the show is recurring, your changes will apply to future instances of that show. 

FCML envelope requirements

FCML only works with flexible paper envelopes that meet USPS letter mail requirements.

Your envelope must:

• Be between 5 and 11½ inches long
• Be between 3½ and 6⅛ inches wide
• Be no more than ¼ inch thick
• Have an even thickness with no lumps or bulky areas
• Bend easily and remain flexible during processing
• Have an aspect ratio (length ÷ height) between 1.3 and 2.5

Don’t use:

• Bubble mailers
• Rigid cardboard or stiff inserts that don't bend
• Plastic sleeves as outer packaging
• Clasps, strings, or buttons
• Uneven or bulky packaging

FCML shipments that don’t meet USPS letter requirements may be refused, returned, delayed, or charged additional postage.

FCML shipping time and limited tracking 

First-Class Mail Letter (FCML) is a slower shipping option. Orders usually arrive within 2 to 10 business days, depending on USPS processing and the buyer's location.

Tracking is limited and only visible on Whatnot. It doesn't appear on the USPS website.

You may see up to three tracking updates in your order details page, including:

• In transit: Accepted by USPS
• Origin processing: Scanned at a USPS facility
• Delivered: Marked as delivered

Tracking updates can take 24 to 72 hours to appear on Whatnot. 

Some shipments may not receive tracking updates at all. This can happen if the envelope is too thick, the barcode is damaged, or USPS sorts the envelope manually.

Limited tracking updates don't usually affect delivery.

Confirm drop-off for FCML shipments

Sellers are expected to ship FCML orders within two business days of the sale to provide a great buyer experience.

Because FCML tracking is limited, confirming drop-off with the in-app scanner is the most reliable way to keep buyers informed and ensure your shipping activity is accurately reflected.

When you scan an FCML shipment at drop-off, you:

• Notify the buyer right away with a photo of their shipment
• Create proof of shipment, giving you added protection if questions around fulfillment timing come up later
• Ensure your Average Ship Time accurately reflects how quickly you ship

If you don’t confirm drop-off, FCML shipments may temporarily appear Overdue in Seller Hub. This status will automatically update to Shipped seven days after label creation if no scan is detected, but this isn’t considered proof of shipment.

How to scan FCML shipments

You can use the in-app scanner and Whatnot manifest (in limited-release) to confirm drop-off.

Before scanning, make sure:

• You have the correct envelope
• The label is clearly visible
• The image on your screen is clear and readable
• You’re comfortable with the image being shared with the buyer

When scanning:

Scan the entire envelope — not just the QR code.
The scanner needs to capture the buyer’s username in order to match it to their shipment and be considered “Shipped”. If multiple shipments exist for a buyer, you’ll be prompted to select the correct one.

If the envelope doesn’t scan automatically, use the shutter button.
Keep the scanner open. After a few seconds without a successful scan, a camera shutter button will appear. Tap it to manually capture a photo and match it to the correct shipment.

How this impacts your performance 

Scanning FCML shipments at drop-off ensures your Average Ship Time reflects when you actually shipped your order, giving buyers a clearer view of your fulfillment speed.

If there’s no proof of shipment and a buyer reports a late delivery that’s escalated to Whatnot Support, the order may be cancelled and refunded.

If your shipment doesn't qualify for FCML

If an order doesn’t meet FCML rules by the time you need to ship, Whatnot will automatically upgrade the shipment to USPS Ground Advantage or Priority Mail.

Here's how it works: 

FAQs

Can I turn on FCML after a sale?

No. FCML must be enabled before your show starts. When turned on, it’ll automatically apply to eligible shipments sold during that show. 

Can I switch from FCML to another shipping method after a sale? 

Yes. You can upgrade the shipment by adjusting the shipment and increasing the package weight to 4 oz or more. This should change the service to Ground Advantage or Priority Mail. 

These upgrades count toward your weekly free shipping adjustment allowance. Additional fees may apply after you use your free adjustment allowance. 

When will I get paid for FCML orders?

Because FCML has limited tracking, payout timing is based on label generation instead of delivery scans:

• Standard payout: Earnings start processing 10 days after label creation.
• Early Payout: Earnings begin processing immediately after you generate the label. 

Once your earnings are available in your account balance, you can start a payout.

Can I use FCML for other categories on Whatnot? 

FCML is only available for Trading Card Games, Sports Cards, and Stickers sold through live shows. We’re exploring if this shipping option can be expanded to other categories in the future.