Card Mailer connector documentation
Card Mailer prints 5×7 photo postcards and mails them USPS First-Class to a list of US addresses. These are the details for using it from Claude or ChatGPT.
Connect
- Claude: Settings → Connectors → Add custom connector. Name: Card Mailer. URL:
https://cards.onmax.me/mcp/claude. No sign-in. - ChatGPT: from the app directory once listed, or in developer mode with
https://cards.onmax.me/mcp.
Tools
| Tool | What it does | Changes data |
|---|---|---|
import_address_list | Reads pasted text, CSV or XLSX addresses (up to 300), checks each against USPS data, returns a list id and the rows to fix. | Creates a draft list |
fix_address | Corrects or removes one recipient by row number and re-checks it. | Edits the draft list |
design_card | Builds the card: greeting and photo on the front, message and sign-off on the back. Takes an attached photo (ChatGPT) or a public image URL. Does not generate images. | Creates or edits a draft design |
quote_mailing | Price, send date and arrival window; with an arrive-by date, the latest safe send date. | No |
create_mailing | Creates an unpaid order and returns a link to https://cards.onmax.me/m/…, where the user reviews and pays with Stripe in the browser. | Creates an unpaid order |
get_mailing_status | Paid, printing, mailed, delivered, with per-recipient counts. | No |
Nothing is printed, mailed or charged inside Claude or ChatGPT. Payment happens only on the order page.
Limits
- US addresses only, including APO/FPO and Puerto Rico.
- Up to 300 recipients per order.
- 5×7 postcards without envelopes; one design per order.
- In Claude, photos must be a public link, because attached images aren't passed to connectors.
Example prompts
Make a holiday card from this photo (link) with “Wishing you a joyful season” and mail it to the addresses in this spreadsheet before Dec 15.
Send a thank-you card to each client in this CSV, signed “The team at Oak & Pine Studio”.
What would 25 cards cost to arrive by December 20?
Troubleshooting
- “list_id not found”: lists are deleted 14 days after creation if no order is paid; import the list again.
- A row says it could not be read: send name, street, city, state and ZIP for that row with
fix_address. - “Card Mailer mails only to US addresses”: remove that row; international mail isn't offered.
- The photo is blurry: use a photo at least 2000 pixels wide.
Privacy
Addresses are used only to print and mail the cards and are deleted 30 days after the send date. See the privacy policy. Support: cards@onmax.me.