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

If you’re a U.S. seller shipping cards or stickers from shows, USPS First-Class Mail Letter (FCML) can be a simple, affordable way to ship small orders in a standard envelope. No fancy packaging needed.

Also known as plain white envelope (PWE) shipping, this option helps keep costs low for you and your buyers.

You’ll need to turn on FCML before your show starts. Once it’s on, it automatically applies to any eligible items sold during that show.

On this page: 

• When you can use FCML
• Why sellers use FCML
• How much FCML costs
• Turn on First-Class Mail Letter shipping
• 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 you can use FCML

You can use First-Class Mail Letter (FCML) if all of the following are true:

• Item criteria:
  • You're selling in Trading Card Games, Sports Cards, or Stickers categories
  • You're selling these items during a live show

  • You've turned on FCML shipping before your show

  • Your items aren't listed using a custom shipping profile or max bundle size
• Shipping requirements:
  • The shipment includes no more than 5 items/cards
  • The total shipment weighs 3 oz or less
  • The total shipment value is $20 or under
  • The buyer is in the US (domestic shipping only) 

Why sellers use FCML

• Cheaper shipping costs: Label prices start at $0.74 (+ fees*).
• Easier to pack: Just use a standard paper business envelope and print the label from Whatnot.
• Faster to drop off: Drop the envelope in any USPS mailbox and skip a trip to the post office. 

How much FCML costs

As of July 13, 2025, FCML labels prices are:

*Note: The total shipping cost for FCML includes the label price listed above, plus a small fee to help cover the operational cost of features like Smart Bundling and Flat-Rate shipping. Whatnot continues to invest in great product experiences and work with our carriers to get preferential rates for our customers. 

Turn on First-Class Mail Letter shipping

Turn FCML on for future shows

If you’re selling items that qualify for First-Class Mail Letter, you can turn it on in your Seller Hub shipping settings. Once it’s on, FCML will automatically apply to eligible orders for future shows.

Note: You can only turn FCML on from your Seller Hub in the Whatnot app. 

Update FCML for a scheduled show

You can also enable FCML for an upcoming show you already scheduled. If it’s a recurring show, these changes will apply to all future instances of that show. 

FCML envelope requirements

When packing an FCML shipment, use a standard paper envelope or flat paper mailer that meets all of these USPS requirements:

• Length: 5–11½ inches
• Width: 3½–6⅛ inches
• Thickness: ¼ inch max, with even thickness and no lumps
• Proportional aspect ratio (length ÷ height): 1.3 to 2.5
  • Example: A 6.5 x 4.25" envelope is OK because the aspect ratio = 1.53

Not accepted: 

• Envelopes with clasps, strings, or buttons
• Plastic sleeves, bubble mailers, cardboard, or other rigid packaging
• Anything that feels stiff, uneven, or can't bend easily 

Sticking to these guidelines helps avoid USPS surcharges, returns, or delays. 

FCML shipping time and limited tracking 

First-Class Mail Letter is a slower shipping option. Orders usually arrive in 2 to 10 business days, depending on USPS and the buyer’s location.

Tracking is limited and only visible on Whatnot. It won’t appear on the USPS website.

You may see up to 3 tracking updates in your Order Status page, for example:

• 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 show up. Some shipments might not be tracked at all. This can happen if the envelope is too thick, the barcode is damaged, or it’s sorted by hand. In most cases, this doesn’t 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 change my shipment to FCML after a sale?

No. You can’t switch to FCML after a sale. FCML must be turned on before your show starts. When it’s enabled ahead of time, it'll be automatically applied to eligible items purchased during your show.

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

Yes. You can switch from FCML to another method (e.g. Ground Advantage or Priority Mail). Just edit the shipment details and increase the weight of the package to 4 oz or more. 

These upgrades count toward your weekly allowance of free shipping adjustments. After that, fees may apply. 

When will I get paid for FCML orders?

First-Class Mail Letter is a special shipment type with limited tracking. Because of this, Whatnot doesn't wait for delivery scans to start processing your earnings.

Instead, your earnings begin processing:

• Standard payout: 10 days after you generate the label.
• Early Payout: Right after you generate the label.

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.