What We Do
SMTP Handshake Verification
We connect directly to the recipient's mail server and simulate an email delivery up to the RCPT TO stage — verifying the address actually exists without sending a message.
STARTTLS Encryption
Full STARTTLS support for servers that require encrypted connections. Secure SMTP handshakes protect verification traffic from interception.
Real-Time Results
Asynchronous job-based architecture returns results in seconds. Queue verifications and poll for completion with built-in request tracing.
Smart Rate Limiting
Per-domain concurrency controls with circuit breaker protection. Automatically backs off on throttled domains to maintain high deliverability.
DNS Intelligence
Built-in MX record resolution with in-memory caching. Identifies catch-all domains, disposable providers, and unverifiable mail servers.
Privacy First
No actual emails are sent. Verification data is automatically purged after 24 hours. We only validate deliverability — nothing more.
How It Works
DNS Lookup
Resolve MX records for the recipient's domain to find the responsible mail server.
SMTP Connect
Open a TCP connection to port 25 on the MX host and receive the server banner.
EHLO & STARTTLS
Identify ourselves and upgrade to TLS encryption if the server supports it.
RCPT TO Check
Issue MAIL FROM and RCPT TO commands. A 250 response confirms the mailbox exists.
System Information
| Service | MailThentic SMTP Worker API — internal verification node for mailthentic.com |
|---|---|
| Endpoint | smtp.mailthentic.com |
| Version | 2.0.0 |
| HELO Domain | smtp.mailthentic.com |
| STARTTLS | Enabled |
| Max Concurrency | 50 parallel verifications |
| Data Retention | 24 hours (auto-purge) |
| API Documentation | Swagger UI · ReDoc |
| Authentication | Bearer Token — All endpoints except /health |
| Parent Platform | mailthentic.com — Email verification SaaS |