LetterAgent
Mail physical letters by just asking your AI assistant.
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They save you from hand-addressing or labeling envelopes: the recipient's address, printed on the letter itself, shows through a cut-out window. A double-window envelope adds a second window for your return address. The catch is alignment: if the letter shifts and part of the address hides behind the envelope paper, the address can't be read by the sorting machines.
The idea is almost embarrassingly simple. You print the letter with the recipient's address block positioned where the envelope's window will be. Fold the letter, slide it in, and the address shows through the opening. Nobody writes on the envelope, nobody sticks on a label, and the address on the envelope can never disagree with the address on the letter, because they are the same printing.
This is why businesses and bulk mailers live on window envelopes: when you are sending hundreds or thousands of letters, hand-addressing is not a task, it is a staffing problem. The window turns addressing into part of printing. It also removes a whole class of error. A mislabeled envelope sends the right letter to the wrong person; a window envelope cannot do that, because the address visible is the one printed on the letter inside.
A single-window envelope shows the recipient's address. A double-window envelope adds a second, smaller window, usually in the upper left, that shows the sender's address printed on the letter. That sender window acts as the return address: if the letter cannot be delivered, the post office knows where to send it back without anyone writing anything by hand.
| Envelope type | Windows | What shows through | Typical use |
|---|---|---|---|
| Single-window (#10) | One, lower left/center | Recipient address | Personal letters, small mailings |
| Double-window (#10) | Two: recipient + upper-left sender | Recipient address and return address | Business correspondence, invoices, notices |
| Full-face window | One large window | Most of the letter's first page | Statements and forms where content is visible |
Alignment is the entire failure mode. If the letter shifts inside the envelope, part of the address disappears behind the paper and the sorting machines cannot read it. The fix is in the fold: for a standard #10 envelope, the letter fold (fold into thirds, like a Z) positions the address block to land on the window. If you fold it wrong, or print the address block in the wrong spot, the window shows blank paper and the letter becomes undeliverable as addressed.
A few more things people learn the hard way. First, the address must sit fully inside the window with every line visible: a ZIP code cut in half is as bad as a missing ZIP code. Second, the clear film over the window is polystyrene plastic, which means the envelope is not plain paper for recycling: the window should be removed before the envelope goes in the paper bin, or the whole thing goes in the trash. Third, window envelopes and inkjet printers are a poor pairing for the address block, because a smudged address behind a window is unreadable and cannot be rewritten by hand the way a smudged envelope can.
Yes: every LetterAgent letter goes out in a standard double-window business envelope. The recipient's address shows through one window and the sender's address through the other, which acts as the return address. Because the address is printed as part of the letter, there is no hand-addressing step and no chance of a label mismatch. If you send through LetterAgent, you will never touch an envelope at all, window or otherwise: describing the letter to your AI assistant is the whole addressing process.
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