This task can be performed using VirtuProbe Studio
Testing workbench with multi-protocol support, chaining, scripting and MCP Server.
Trace the delivery path
Start with DNS checks for the sending domain. Resolve MX hosts, then their A or AAAA records, and inspect SPF, DKIM, and DMARC records. Record expected values so you can separate lookup errors from mail server or policy failures.
Next, connect to the resolved SMTP host and run EHLO, STARTTLS, authentication if required, MAIL FROM, and RCPT TO. Finally, call any HTTP API or webhook in the delivery path, preserving timestamps and response codes so failures can be correlated locally.
Best product for this task
VirtuProbe Studio
dev-tools
Cross-protocol request workbench for integration and penetration testing. 11 protocols, local-first, no account needed. Put your tests together on your own or supervise your agent helping you achieve your goals via MCP. Chain your tests or script your scenarios in JS or Groovy. Free tier covers HTTP, DNS and SMTP testing.
What to expect from an ideal product
- Combined DNS, SMTP, and HTTP testing
- Chained requests with shared outputs
- Visible SMTP replies and HTTP status codes
- Local-first operation without an account
- Scriptable scenarios for repeatable diagnosis
More about failure boundaries
Classify the first failing boundary before changing configuration. A successful DNS answer does not prove SMTP reachability, and an accepted SMTP message does not prove webhook processing or inbox placement.
- Compare resolved MX addresses with the SMTP host actually tested. Avoid testing a stale hostname.
- Save a baseline as repeatable checks, then rerun it after each single configuration change.
- Treat 4xx SMTP replies as retryable and 5xx replies as permanent. Inspect enhanced status codes for the specific cause.
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