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If your CRM isn’t one of Mailr’s native connections and Zapier can’t reach it, your own systems can talk to Mailr directly through the Mailr Developer API. Your software tells Mailr when something happened — a job finished, a deal closed, a new contact arrived — and Mailr mails the neighbors around that address. This page is the non-technical half: what’s possible, what it looks like inside Mailr, and what to hand your developer. The technical half lives in the API Reference.

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What you can do with it

  • Trigger campaigns from your own events. Your system sends an event with the job’s address; a matching automation queues a postcard campaign to that street.
  • Receive leads back. When someone scans a postcard and fills in the landing page, Mailr can push that lead straight into your software. See Receive leads.
  • Report won deals. Send the sale back so revenue attaches to the campaign that mailed that home.
Check the integrations list first. If your CRM is one of the 14 native connections, connect it there instead — nothing to build, and the same triggers, lead sync and revenue tracking.

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Where it shows up in Mailr

There’s no tile to click and no key to paste into Mailr. Your API key is the connection, and the option appears on its own once your systems have sent at least one real event. Open Campaigns → Automations in the Mailr app, create or edit an automation, and look under Automation details, below the CRM trigger options: a row reading Trigger from your API. Only the workspace Owner can create or edit automations — see Team & roles. Open it and the panel explains itself:
“Fires the moment your integration posts the event. The postcard mails around the address on the record automatically.”
  • Event — a dropdown of the events your systems have actually sent, grouped as Job events, Deal events and Contact events. Each line shows a readable name plus your own event name in parentheses, like Job Completed (job.completed). Mailr never invents this list: “These are the events your integration has sent us.”
  • Refresh events — pulls the list again after your developer sends something new. Before anything arrives you’ll see “No events received yet — send an event from your integration, then refresh.”
  • Only send a postcard when… (optional — all rules must match) — the same filters as any CRM trigger. Pick a Property from the fields your events carried, an operator (equals, contains, is at least, is filled, and so on) and a Value. Press + Add filter for more, up to 10 rules.
  • A recap line spells the rule out: Fires when your API sends a “Job Completed” event — only if your filters match, and “Fires instantly, as soon as your API posts the event.”
The panel also warns that events without a street address (plus a city or ZIP) are skipped — no address, no postcard. There’s no pipeline or stage to pick here; filter on properties instead. Everything else about the automation is unchanged: neighbors per install, property filters, card type, template, landing page, follow-up drops, automatic review, your cooldowns and your do-not-mail list all work exactly as they do for a connected CRM. Saved automations show a Your API pill on the card instead of a CRM logo. See Automate campaigns.

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What you and your developer need

1

Create an API key

Go to your workspace name → Manage account → API keys and create a key. Only the workspace Owner can create keys. Copy it once and hand it over — it isn’t shown again.
2

Hand your developer the API reference

Point them at the API overview and Send events. Nothing else is configured on your side.
3

Have them send a test that mails nothing

The API accepts a test (“dry run”) event: it runs every check and reports what would have happened, but writes nothing and mails nothing.
4

Send one real event, then build the automation

A real event is what teaches Mailr your event names. Once it lands, press Refresh events in the automation editor and pick it from the Event dropdown. Then walk the go-live checklist before pointing real traffic at Mailr.

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Zapier or the API?

Both end up in the same place — an automation with your postcard settings — so starting on Zapier and moving later costs you nothing.

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Common questions

Nothing mails. Mailr accepts the event, tells your system that no automation matched, and creates no campaign. That’s normal early on — your first events exist mainly to fill the Event dropdown so you can build the automation.
Yes. A test (“dry run”) event runs the whole path — matching, filters, address check — and reports what would have happened without creating a campaign or spending credits. One catch: because a test writes nothing, it doesn’t add your event to the Event dropdown. Send one real event for that.
Not if your integration sends the lead back the way the API describes. Mailr puts an identifier on every lead it delivers to you; when your event carries that identifier back, Mailr recognizes its own lead and skips it, so a lead Mailr sourced can’t make Mailr mail that address’s neighbors again. If the identifier isn’t sent back, Mailr has no way to tell — Send events shows your developer what to echo.
No. Custom Campaign Trigger belongs to the Mailr app for Zapier. Trigger from your API is your own software talking to Mailr directly. Pick one per automation.

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Next steps

API reference

Hand this to your developer — keys, events, leads and revenue.

Send events

The event your system sends to start a campaign.

Automate campaigns

Build the automation your events will fire.

Contact support

Not sure which path fits your setup? Ask us.