Sending Certified Mail

Getting Started

Certified Mail is a secure and trackable way to send important documents. This guide covers different certified mail scenarios, including sending to PO Boxes, international destinations, right from your home or office using LetterStream.

In This Article

Sending Certified Mail

LetterStream makes it easy to send Certified Mail without leaving your home or office:

  • No need for envelopes, stamps, or printers.
  • LetterStream handles printing, folding, inserting, and mailing.
  • You simply upload your documents and choose your mail type.

For more information on getting started, click here.

Send Certified Mail to a PO Box

Yes, you can send Certified Mail to a PO Box, but the process differs from mailing to a physical address:

  • Physical Address: USPS attempts delivery and captures a signature from an authorized recipient (unless you opt out of requiring a signature).
  • PO Box: USPS places a pickup notice in the recipient’s box. The recipient must go to the front desk and sign for the item.

If you send Certified Mail using LetterStream, the signature file is saved in your account for easy access—no need to manage physical green cards.

Send Certified Mail Internationally

Certified Mail is not available for international deliveries.

For international mail that requires tracking or proof of delivery, the USPS offers Registered Mail:

  • Registered Mail is available through LetterStream.
  • It provides delivery confirmation and tracking, though neither are guaranteed.
  • Be aware: Registered Mail is significantly more expensive than Certified Mail.

For more information, click here.

Maximum Weight Capacity For Certified Mail

Certified Mail flats have a limit of 75 sheets. If your document exceeds this limit, our system will automatically adjust the packaging and delivery method to ensure it is mailed properly.

For example, Priority Certified Mail can exceed the 13-ounce (75-sheet) limit. While this option isn’t available for customers to select directly, our system will automatically detect when a Certified mailing exceeds the limit and upgrade it to Priority Certified Mail, shipping it in a box.

You’ll be notified of this during the job creation process, but no action is required on your part.


Certified Mail is Unpredictable

Certified Mail should be used only when you are required. Certified Mail provides proof that a letter was mailed and accepted by the USPS, but it does not guarantee delivery, signature capture, or clear tracking updates. Delays, missing scans, and incomplete delivery information are common and are considered normal USPS behavior.

Because Certified Mail does not offer delivery guarantees or predictable outcomes, it is not recommended when delivery timing, confirmation, or reliability is critical.

If you are not required to use Certified Mail and want clearer tracking and more dependable delivery confirmation, we recommend FedEx 2Day. FedEx generally provides more consistent tracking, clearer delivery scans, and stronger accountability than USPS Certified Mail.

In short:

  • Use Certified Mail only when required and when USPS limitations are acceptable
  • Use FedEx 2Day when reliability and visibility matter

Once a mailing is handed off to the carrier, LetterStream has fulfilled its responsibility by mailing the letter in good faith, and carrier-related outcomes are outside of our control.