Send mail from a Slack message
Turn a Slack message or slash command into a mailed letter: pair Slack’s own Zapier, Make, or n8n trigger with paperplane’s Send Letter action so a #send-mail channel post becomes a real, USPS-verified letter from $1.99.
Via Zapier, Make, or n8n — no direct app yet
Instead of a #print-this channel
A channel where someone is asked to print and mail a thing depends on that someone. The trigger reads the message, the action mails it, and the status comes back into the thread.
How to set it up
- 1In Zapier, Make, or n8n, use Slack’s "New Message Posted to Channel" trigger (or a custom slash command) on a channel dedicated to mail requests.
- 2Add the paperplane Send Letter action, mapping the message text into the letter body and parsing the recipient address from the message or a fixed lookup.
- 3Test with Sandbox on first — the whole pipeline runs free and instantly, and nothing mails.
- 4Go live; the automation can post the order status or a confirmation link back into the same Slack thread.
What the action sends from a Slack message
{
"mail_class": "first_class",
"sandbox": true,
"text": "Dear Ms. Alvarez, ...",
"to": { "name": "Maria Alvarez", "line1": "1 Main St",
"city": "Richmond", "state": "VA", "zip": "23220" },
"from": { "name": "Alex Rivera", "line1": "12 Grove Ave",
"city": "Richmond", "state": "VA", "zip": "23221" },
"email": "alex@example.com"
}Under the hood
This wraps Slack’s standard message trigger, already well-supported in Zapier, Make, and n8n, with the same Send Letter action as everything else here — no paperplane-specific Slack app exists yet, so the pattern to parse an address out of free-form message text has to live in the automation step (a regex, a lookup table, or a structured slash-command syntax).
Supported action fields
Every integration maps into the same fixed set of fields, the ones the REST API and MCP tools take directly.
| Field | What it does |
|---|---|
| mail_class | first_class, certified, certified_return_receipt, or priority |
| text or pdf_url | the letter body as plain text, or a fetchable PDF to print as-is |
| to | recipient name + street/city/state/zip, verified against USPS data |
| from | return address, printed on the envelope and used for undeliverable mail |
| where the receipt and status updates go — no account required |
Popular Slack workflows
Or skip the automation tool: ask Claude or ChatGPT
Every integration here sits on the same MCP endpoint agents use directly. Instead of wiring a trigger to an action, ask Claude or ChatGPT to draft and mail the letter. Same three tools (quote_letter, send_letter, get_letter_status), same price, same free sandbox.
Related integrations
Stripe
Google Forms
AirtableSend your first letter from Slack.
Sandbox runs the whole pipeline for free and mails nothing. Live sends start at $1.99, one all-in price.
curl -X POST https://sendpaperplane.com/v1/orders \
-H 'Content-Type: application/json' \
-d '{
"mail_class": "first_class",
"sandbox": true,
"text": "Dear Ms. Alvarez, ...",
"to": { "name": "Maria Alvarez", "line1": "1 Main St",
"city": "Richmond", "state": "VA", "zip": "23220" },
"from": { "name": "Alex Rivera", "line1": "12 Grove Ave",
"city": "Richmond", "state": "VA", "zip": "23221" },
"email": "alex@example.com"
}'Common questions
Does the message need a strict format?
It helps — a slash command with fixed fields (recipient, address, letter text) parses far more reliably than free-form chat text. A short template posted as a pinned message works well for a team channel.
Can teammates approve the letter before it mails?
Yes — run the automation with Sandbox on first and have it post the quote back to the thread; a reaction or a second message can gate turning Sandbox off.
Is there a paperplane Slack app?
Not yet — this uses Slack’s own well-supported Zapier/Make/n8n triggers, the same as HubSpot and Airtable on this directory.