Slack → certified letter
Post a request in a #send-mail Slack channel and paperplane’s Send Letter action mails it Certified — from $12.99, with proof of mailing, no leaving Slack to fill out a form.
All Slack integration options · All integrations
Supported triggers and actions
| Trigger | Action |
|---|---|
| New message posted to a channel (e.g. #send-mail) | Send Letter, mail class from the message |
| Custom slash command (e.g. /mail-certified) | Send Letter, fields from the command’s structured input |
How to set it up
- 1In Zapier, Make, or n8n, use Slack’s "New Message Posted to Channel" trigger, or build a slash command with fixed fields for recipient, address, and letter text.
- 2Add the paperplane Send Letter action and map the parsed fields in, setting mail_class to certified for legal or important notices.
- 3Sandbox-test with a real message first — free, instant, nothing mailed.
- 4Go live, and have the automation post the order id and status back into the same Slack thread as confirmation.
What the action sends from a Slack request
{
"mail_class": "certified",
"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
A structured slash command (fixed fields for recipient, address, and body) parses far more reliably into the Send Letter action than free-form chat text — treat the Slack message as the trigger and the address-formatting logic as something the automation step, not paperplane, has to do. No paperplane-specific Slack app exists yet.
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.
Send 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"
}'Slack integration options · All integrations
Common questions
Do teammates need to leave Slack to send the letter?
No — the whole flow (draft, quote, confirm) can live in the Slack thread; the automation calls paperplane in the background and posts the result back.
Can someone approve the letter before it actually mails?
Yes — run with Sandbox on and post the quote to the thread first; a thumbs-up reaction or reply can gate the live send in a second automation step.
Why Certified Mail for this one specifically?
Slack-triggered sends tend to be one-off, time-sensitive notices (a compliance letter, a formal notice) where proof of mailing matters — but any mail_class works the same way.