Everything that happens after submit.
You handle the frontend. Postbox handles validation, spam filtering, translation, replies, and delivery. One endpoint, any source.
The processing pipeline
Receive
Accept submissions from HTML forms, API calls, scripts, or AI agents. JSON or form-encoded. CORS handled.
Validate
Schema-based validation. Required fields, types, and constraints enforced before anything else runs.
Filter
Heuristic and AI spam detection. Honeypot fields, disposable email blocking, and content moderation.
Deliver
Email notifications, webhook delivery, and dashboard access. Your data arrives where you need it.
AI-powered features
Intelligent spam detection
AI-powered spam scoring that goes beyond heuristics. Catches sophisticated spam that pattern matching misses. Uses 1 AI credit per submission.
Auto-translation
Submissions arrive in your language. Source language auto-detected, translation happens before you see it. Originals always preserved. 1 credit per submission.
Smart replies
Connect a knowledge base. Postbox drafts contextual replies grounded in your docs. Review and send, or automate fully. 2 credits per reply.
Built for developers and agents
REST API
Full CRUD API for forms and submissions. Create forms, query data, and manage everything programmatically with your API key.
MCP server
Connect from Claude, Cursor, or any MCP client. Your AI assistant can create forms, query submissions, and manage data without leaving your editor.
Schema versioning
Change your fields anytime. Every change produces a new endpoint URL. Every existing URL keeps working. Nothing breaks.
Webhooks
Forward submissions to any URL. Configurable per form with retry logic and delivery tracking.
llms.txt
Machine-readable documentation at /llms.txt. AI agents can discover your API without human help.
CORS & form-encoded
Submit from any origin. JSON or form-encoded bodies both accepted. OPTIONS preflight handled automatically.
No credit card required. View pricing