LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > International letters and customs
No: ordinary letters and documents crossing a border need no customs forms. Customs is for goods, not paper: invoices, contracts, personal letters, and tax documents travel without any customs paperwork. The line that matters is documents versus goods: the moment an envelope contains something with value beyond the paper itself, you're in customs territory.
| Contents | Customs form needed? | Why |
|---|---|---|
| Correspondence, invoices, contracts, statements | No | These are documents: information on paper with no resale value as objects. |
| Photos, printed certificates, legal filings | No | Still documents, even if they're personally important. |
| Checks or money orders | No customs form | Negotiable instruments travel as documents, though some countries restrict mailing cash outright. |
| USB drives, SIM cards, memory cards | Yes: declare them | Electronic media counts as goods in most postal systems. |
| Product samples, parts, merchandise | Yes: declare them | Anything with commercial value is goods, even a "free sample." |
| Cash | Often prohibited outright | Many countries ban cash in the mail; check the destination's rules. |
The gray zone people actually hit: a "document" that has intrinsic value: share certificates, bearer bonds, original artwork on paper. When in doubt, treat it as goods and declare it, or use a courier that handles the declaration for you. Under-declaring to save a fee is the one mistake that reliably gets mail seized.
Every country maintains its own list of what's allowed in the mail, and the lists are genuinely different: what's routine in one country is seized in another. Medications, seeds, food items, and certain printed materials are common restricted categories. There is no master list to memorize; before mailing anything beyond plain documents internationally, check the destination country's postal rules through your own postal service (USPS and Canada Post both publish country-by-country guides). This takes five minutes and is the single highest-value step in international mailing.
One more practical note: for letters between the US and Canada specifically, none of this applies: it's just a letter, addressed in the destination country's format, with no customs involvement at all.
No. LetterAgent mails letters to US and Canadian recipients: these are documents in standard business envelopes, so no customs forms are involved. LetterAgent also doesn't do inserts or parcels: the envelope carries just the letter itself. If you need to send goods across a border, use a parcel carrier or your postal service's parcel product, which will walk you through the customs declaration.
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