LetterAgent

Mail physical letters by just asking your AI assistant.

Status: LetterAgent is currently in private testing ahead of public launch. Everything on this page describes the service as it works today.

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How do I know if my envelope needs extra postage?

An envelope needs extra postage when it weighs more than one ounce, is thicker than a quarter inch, feels rigid, is lumpy, or is square. A quick weigh on a kitchen scale and a simple flexibility test catch nearly every case before the envelope leaves your hands. When in doubt, take it to the counter: clerks weigh and measure it in seconds.

What are the warning signs?

Weight. A single stamp covers up to one ounce. Three or four sheets of standard paper plus the envelope sit right at the edge of that, so a five-page letter is the classic tipping point.
Thickness. Anything thicker than a quarter inch stops being a letter in the machines' eyes. The pencil test works: a standard pencil is about a quarter inch across, so if your envelope is fatter than a pencil, it needs more postage.
Rigidity. Letters have to flex to ride the sorting rollers. A CD, a key, a thick stack of business cards, or a rigid photo mailer will not bend, and rigid pieces get pulled out for hand processing with a surcharge.
Lumps and clasps. Metal clasps, string-and-button closures, wax seals, and anything poking out make the piece nonmachinable. The machines are built for flat paper, and anything that catches gets diverted.
Square shape. Square envelopes cannot be oriented by the sorting machines, so they are processed by hand. A square invitation always costs more than a rectangular one of the same weight.

How can I test it at home?

Test	How to do it	What a fail means
The scale test	Weigh the sealed envelope on a kitchen scale	Over one ounce: add postage for the extra weight
The pencil test	Hold a pencil against the envelope's thickest point	Thicker than the pencil (a quarter inch): package pricing territory
The bend test	Try to flex the envelope gently in the middle	It will not bend: rigid pieces need the nonmachinable surcharge or package rate
The feel test	Run your fingers over the surface	Lumps, clasps, or sharp edges: hand processing, which costs extra

What happens if I guess wrong?

Three outcomes, none of them good. If the piece is underpaid, the post office returns it to you for more postage, which costs days. If there is no return address, it goes forward and the recipient is asked to pay the shortfall, which is an awkward gift to send someone. And if a thick rigid piece jams a sorting machine, the delay is not measured in days but in a damaged or lost letter. Overpaying slightly beats underpaying every time: an extra stamp you did not strictly need costs cents, while a returned letter costs the whole timeline.

When should I just go to the counter?

Whenever two warning signs appear together: thick and rigid, heavy and lumpy, square and thick. Clerks have a template slot that measures thickness instantly and a scale for weight, and they will tell you the exact postage in under a minute. There is also a hard rule to know in the US: a stamped piece over 10 ounces or thicker than half an inch cannot be dropped in a collection box at all and must be handed over at the counter. If your envelope is anywhere near those thresholds, the counter was always the right call.

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Ready to mail it? Send your letter with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is printed and mailed.

LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.

Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com