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Send agent-drafted letters through a mail API, with approval
Sales, CRM & outreach · checked 2026-10-18
Research a short business list, draft and approve each letter, then use a documented mail API or Handwrytten’s Claude connection. Optional per-letter links measure visits without proving who read the letter.
Independent review. IonBin has no partnership with any tool on this page and was not paid for this page. Our evaluation is our own, based on public documentation and our research. Product names are trademarks of their owners and are used for identification only. How disclosure works.
Goal
Reach owners who ignore email with a letter that is actually about their business.
Connects through: API · Built-in integration
Not advice
IonBin provides general information and software comparisons, not tax, legal, accounting or financial advice. Tax and legal rules vary by situation and jurisdiction; consult a qualified professional (CPA, enrolled agent or attorney) before acting.
AI tools can make mistakes. Verify every figure against the original documents and official IRS or state guidance before filing or signing.
Redact Social Security numbers, account numbers and EINs before uploading documents to any AI assistant, and check its data-retention settings. Upload originals only to the filing or signing software.
Requirements vary by state. File through official sources such as the USPTO trademark search and your state’s Secretary of State site.
Follow up by phone or a second letter with businesses that visited or replied
Human stepConfirmed
Confirmed means the vendor documents it (linked). It doesn't mean IonBin has tested it. AI-platform and human steps need no source.
Human approval
You approve every letter before it is mailed.
Watch out for
Verify every fact, address and final price. A unique-link visit does not identify a person or grant consent for follow-up. This is general information, not legal advice.
Starter prompt
Research these 20 businesses from their public websites and reviews. For each, write a 120-word letter that names one specific, verifiable detail about them and one way I could help. Flag any letter where you are unsure of a fact. Do not send anything.
Written for this workflow. Paste it into your AI platform and adjust it to your situation.
Handwrytten or Lob: verify the API caller, network access and credentials; platform code execution alone does not establish this connection
ChatGPT
To verify
Handwrytten or Lob: verify the API caller, network access and credentials; platform code execution alone does not establish this connection
Gemini
To verify
Handwrytten or Lob: verify the API caller, network access and credentials; platform code execution alone does not establish this connection
Perplexity
To verify
Handwrytten or Lob: verify the API caller, network access and credentials; platform code execution alone does not establish this connection
Readiness considers the connection evidence and unresolved steps. Confirmed: documented access and the proposed steps meet the recorded requirements. MCP and API pairings require an explicit reviewed platform note; a named plugin or CLI alone does not confirm MCP. Inferred: an explicit page note describes a plausible pairing that still needs testing. To verify: a connection or step is unresolved. An API and code execution alone do not establish compatible network access, credentials or permissions. None of this is IonBin testing.
This is general information, not legal advice. If you follow up by email, phone or text, CAN-SPAM and telemarketing consent rules apply to those messages.
What we checked (2026-10-18)
Mail APIs. Handwrytten’s API supports card orders and baskets. Its test mode can authorize a payment without capturing it or fulfilling the order. Lob documents letters, postcards and self-mailers; its test key renders proofs but never actually verifies an address. Address verification and real mail require live requests.
Cost. Handwrytten cards retail at $3.75 plus postage. Business Pro displays $449 per month, but the monthly business plans bill every four weeks; its $1.99 card rate and postage are additional. Lob’s Developer plan has no subscription fee and charges print and postage per piece. Startup starts at $260 a month.
Tracking. PostHog web analytics counts visits and sources. A unique link attributes a visit to that link, not necessarily its intended recipient: it can be forwarded or opened by a scanner. Do not report a visit as proof that a named person read the letter.
Follow-ups. Email follow-ups that promote something fall under CAN-SPAM (honest headers, a physical address, an opt-out). Phone and text follow-ups have separate consent and telemarketing rules that depend on the technology, purpose, recipient and jurisdiction. Check those before contacting someone; a landing-page visit is not consent to call or text.
Another documented route
Handwrytten now documents a Claude connection over MCP. It can prepare a card and basket through chat after account authorization. Review the preview, recipients and full cost before approving the send. This is a documented option, not an IonBin-tested purchase.
Set it up
Start with a small batch and preview the final artwork, recipient addresses, postage and total cost. Understand each test mode’s billing and address-verification limits.
Approve each one, and keep a log of what was sent to whom.
Follow up by hand.
Credit: the idea comes from an Instagram reel on agent-written direct mail by creator Angus Sewell. IonBin reviewed the documented components; no orders were submitted and this complete workflow has not been tested; the credit is not an endorsement.
Verification limits and implementation checks
The page is documentation-reviewed; the complete workflow has not been run by IonBin.
The Lob API reference could not be retrieved; official help documents corroborate the formats and test/live behavior.
No mail was purchased or sent. Confirm account prices and production behavior before use.
Sources
Handwrytten API · Handwrytten · official · accessed 2026-10-18
No affiliate links on this page. No paid placements in workflows. How IonBin makes money.
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