If you'd rather not add Zapier as a middle system, HubSpot Workflows can send data straight to a LettrLabs webhook URL. This guide assumes you've already read Setup Guide: HubSpot for the trigger/campaign concepts — this version just swaps the "how it's wired" step.
Before you start
A LettrLabs Open API key and an inbound webhook connection (see Setup Guide: Open API & Webhooks if you haven't set these up yet).
A HubSpot workflow with edit access, on a plan that includes workflow webhook actions.
Knowing which HubSpot event should trigger the mailing (same choices as the Zapier guide).
Step 1: Create your LettrLabs webhook connection
In LettrLabs, go to Automations > Open API and generate an Open API key (or reuse an existing one).
Go to Active Webhooks > Data Streams (Inbound), click Create, and name the connection something you'll recognize later (e.g., "HubSpot — Closed Won").
Copy the generated Webhook URL.
Turn on OpenAPI Key authentication for this connection.
Leave the connection in Test Mode for now — you'll wire it to an actual mailing in Step 4, once you have a real sample payload to map from.
Step 2: Build the HubSpot workflow
In HubSpot, go to Automation > Workflows and open (or create) the workflow for your trigger object — Contact, Deal, Company, Ticket, or a custom object.
Set your enrollment trigger, the same way you would for the Zapier version — for example, Deal Stage is Closed Won, or a form submission on a specific form.
Add an action step and look for the webhook action (labeled Webhook or Trigger a webhook depending on your HubSpot plan).
Set the Method to POST and paste in the LettrLabs Webhook URL from Step 1.
Add a custom header named
X-API-KEYwith your Open API key as the value.If your version of the action lets you choose which properties to include, send at minimum first name, last name, and address. If your version only supports sending the entire enrolled record, that's fine too — you'll pick the specific fields you need out of it in Step 4.
Step 3: Send a test and confirm it arrives
Enroll a test record (or use HubSpot's built-in workflow testing tool) to fire the webhook action once, then check the History tab on your webhook connection in LettrLabs to confirm the request came through. The connection is still in Test Mode at this point, so nothing is mailed — this step just gets you a real sample payload to map fields from.
Step 4: Wire the connection to a mailing and map fields
Open the Automation (Integration Order) — or the Radius Mail setup — you want this webhook to feed, and under Select Webhook Connection, choose the HubSpot connection you just created.
Choose Mail to Recipients (mail the HubSpot contact directly) or Radius Mail (mail the neighbors around an address in the payload).
Map the fields from your Step 3 test payload onto LettrLabs' recipient fields. See the Inbound Webhook Reference for the full list per action type.
Optionally, add Inbound Filters here instead of building extra HubSpot workflow branches.
Step 5: Go live
Save the webhook connection with a name (this turns Test Mode off) and make sure the HubSpot workflow itself is turned on. From here, every enrollment that reaches the webhook action becomes a real, mailed recipient.
Zapier or native webhook — which should you use?
Zapier (Setup Guide: HubSpot) is the faster starting point if nobody on your team is deeply comfortable building HubSpot Workflow logic.
Native webhook (this guide) skips Zapier entirely, avoids Zapier task limits, and — on newer HubSpot plans — lets you choose exactly which properties get sent.
Note: the webhook action's exact name and available options can vary a little by HubSpot plan — if what you see doesn't quite match the labels above, look for the closest equivalent under your Workflow's action menu.
Want help wiring your first HubSpot workflow to a LettrLabs webhook? Reach out to our team.