Postmark + Formspring: send form submissions in real time
Formspring + Postmark = instant transactional email on every submission: autoresponders to the submitter, internal alerts to your team, escalation emails based on form content. Formspring delivers to a small Postmark-aware relay (or Postmark's own webhooks) which sends the templated email.
Setup in 5 steps
- In Postmark, create an incoming webhook URL (or equivalent) and copy it.
- In Formspring, open your form → Webhooks → Add webhook → paste the URL.
- Pick events to deliver (default: every successful submission).
- Save and send a test submission. The Formspring delivery log shows the response.
- Verify HMAC signatures in Postmark (or your relay) using
X-Formspring-Signature: t=…,v1=….
Code examples
https://hooks.postmark.com/services/T0000/B0000/XXXXXXXXXWebhook payload shape
{
"submission_id": "fsm_01HRX...",
"form_id": "frm_abc123",
"created_at": "2026-05-07T10:24:00Z",
"data": {
"name": "Jane Doe",
"email": "jane@example.com",
"message": "…"
},
"meta": {
"ip": "203.0.113.10",
"user_agent": "Mozilla/5.0…",
"spam_score": 0.02
}
}Why connect Postmark to Formspring
Real-time form notifications without polling. The moment a submission lands, Postmark hears about it via signed webhook. Replace email-based form alerts with structured channel notifications, threaded conversations, or programmatic workflow triggers.
Reliability and retries
Formspring retries failed deliveries with exponential backoff (5 attempts over 24 hours). Every attempt is logged in the dashboard with response code, latency, and body. Use the Replay button to re-fire any past delivery.
Security: HMAC signing
Every webhook request to Postmark (or your relay) carries an X-Formspring-Signature: t=<timestamp>,v1=<sha256-hmac> header. Verify in 3 lines (constant-time compare) to confirm the request came from Formspring and wasn't tampered with.
Custom payload shape
On Pro+ plans, you can transform the payload before delivery - pick fields, rename them, add static metadata, or filter by spam score. Useful when Postmark's expected shape doesn't match Formspring's default.