Via Zapier, Make, or n8n — no direct app yet

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 $0.99.

From $0.99 · postage included · no account needed

What the action sends from a Slack messageExample

{
  "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",

paperplane · Slack

Mail this deliverable to the client, certified.

Here’s the draft. I’ll get a quote before anything is sent.

Total, postage included$12.99

Sandbox free · holds 30 minApprove to send

Nothing prints until you approve. Order ord_8k2d.

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 it works

Set up Slack in three steps.

Via Zapier, Make, or n8n — no direct app yet

Step 01
Watch a channel
Use Slack’s “New Message Posted to Channel” trigger (or a custom slash command) on a mail-requests channel.
Step 02
Map the message
Add the Send Letter action, mapping the message text into the letter body and parsing the recipient.
Step 03
Sandbox, then post back
Test with Sandbox on, then go live; the automation can post the order status back into the same thread.

Copy the config.

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_err (Certified with electronic 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
email	where the receipt and status updates go — no account required

Popular Slack workflows

Slack → certified letter

A message is posted to a specific Slack channel, or a slash command is run.

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 mailing tools (quote_letter, send_letter, get_letter_status), same price, same free sandbox.

Send mail from Claude Send mail from ChatGPT

Send your first letter from Slack.

Sandbox runs the whole pipeline for free and mails nothing. Live sends start at $0.99, one all-in price.

Send a letter

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.