LetterAgent
Mail physical letters by just asking your AI assistant.
Postage due means there wasn't enough postage on a letter, so the recipient has to pay the shortfall before receiving it. It usually happens with overweight, oversized, or oddly shaped mail, or stamps that don't add up to the current rate. To avoid it, weigh the letter and buy enough postage. LetterAgent quotes include postage, so it never comes up.
Somewhere between the mailbox and the destination, the post office weighed or measured the letter and found the postage short. The usual culprits:
| Cause | Example | The fix |
|---|---|---|
| Over one ounce | Extra pages, photos, or heavy paper | Weigh it and add postage for the extra weight |
| Nonmachinable shape | Square, rigid, or lumpy envelopes | Pay the nonmachinable surcharge |
| Short-paid stamps | Old stamp values that no longer cover the rate | Check current rates before mailing |
| International underpayment | Domestic postage on a letter going abroad | Use proper international postage |
The carrier doesn't just leave it in the mailbox. The envelope gets stamped with the amount due, and the recipient has to pay that amount to receive it. Most people find this annoying, which is worth remembering if you're mailing something to a customer or a landlord: making the recipient pay for your underpaid letter is a bad first impression.
The recipient can also refuse it. If they do, or if nobody pays, the letter is held for a while and eventually returned to the sender. Either way, delivery is delayed by days while the payment question gets sorted out.
Square envelopes are the classic surprise. They cost extra postage not because of weight but because of shape: sorting machines orient envelopes by their length, and a square envelope has no long side to read, so it has to be handled by hand. Anything rigid, lumpy, or fastened with clasps or string gets the same treatment and the same surcharge.
Two smaller gotchas: tape over a stamp can make it unreadable to the canceling machines, which can flag the letter, and glossy or coated envelopes sometimes slip through the machines badly enough to need hand processing. Plain paper envelopes with cleanly affixed stamps move through the system with the least friction.
A cheap kitchen scale is the whole solution for most people: weigh the sealed envelope, check the current rate, and round up if you're between weights. If you're unsure, the post office counter will weigh it and sell you exactly the right postage. Online postage tools calculate it for you when you enter the weight and destination.
And if you'd rather skip the scale math, that's part of what mailing services are for. With LetterAgent, the per-letter quote you approve already includes the correct postage for the letter as quoted, so the recipient never sees a postage-due stamp.
Ready to mail it? Send your letter with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it's 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