Legal correspondence for solo attorneys and small firms
By Justin Winter · Updated September 16, 2026
The short answer
Solo attorneys and small firms can send Certified legal correspondence — demand letters, notice letters, lien warnings — for $12.99 ($14.99 with electronic Return Receipt) per piece, by upload or API, with the letter in USPS hands the next business day.
The math
The break-even on one letter.
$14.99 divided by the hours the errand takes is the hourly rate at which paperplane costs the same as your time. A 30-minute round trip, for example, breaks even at about $30 an hour. Use your own figures.
Usually the right pick: Certified + Return Receipt · $14.99
For a solo practice, the errand is the expensive part of legal mail: someone at the firm stands at a Certified Mail counter filling out forms by hand. Here it is $14.99 all-in for Certified with electronic Return Receipt, sent from the desk in about two minutes. The break-even above shows when that beats the trip.
The workflow fits how firms actually send: finalize the letter in Word, export a text PDF (up to 12 pages, exhibits included), upload, address, pay. The status page tracks screening → printing → in the mail → delivered, and the electronic Return Receipt lands in email when signed for — attach it straight to the matter file.
What this is honestly for: correspondence — demands, statutory notices, preservation letters, settlement communications. It is not process service (use a process server where personal service is required) and not a substitute for e-filing. For the middle mass of "must be mailed, must be provable" letters, it removes the errand entirely.
Firms with volume can wire it into practice management via the REST API — POST /v1/orders from your document pipeline — and prepaid credits keep billing simple with one receipt per pack. Sandbox mode lets your admin test the full flow for free before the first real letter.
This page is general information about USPS mailing options, not legal advice. Notice rules vary by state and by document. Check your lease, contract or local rules, or ask an attorney, before relying on it for a deadline.
Questions before you send
Why not go to the post office myself?
You can, and if your time is free it costs less. USPS charges the same fees whoever hands the letter over; paperplane does not replace the post office, it replaces the trip. The mailing record comes from USPS, not from us. $12.99 covers the printing, the envelope, PS Form 3800, a USPS address check before you pay and a handoff the next business day. For a letter you already know how to send, the counter is a fine choice.
What if they refuse the letter?
USPS tracking records what happened to it, including refused or unclaimed. You still have the mailing record. Rules on what that means vary, so check with your court or an attorney if a deadline depends on it.
If something goes wrong, do I pay?
If we cannot mail the letter, the hold on your card is released and you are not charged. If a letter fails after your card is charged, you are refunded automatically and in full.
Is the electronic Return Receipt admissible as proof of delivery?
The USPS electronic Return Receipt is the digital successor to the green card and is commonly used as delivery evidence. We deliver it to your email; retention beyond 30 days is your side, so file it with the matter.
Can we send on behalf of clients?
Yes — the sender address on the letter is whatever return address you specify, e.g. the firm. Screening allows lawful attorney correspondence explicitly, including firm demand language.
Does this work for service of process?
No — where rules require personal service or specific service procedures, use a process server. This is for correspondence and notices where mailing (or certified mailing) is the requirement.