Email Technical Online Tools Collection

Free browser-based tools · IETF RFC based · Zero data collection

This page collects all free online email technical tools provided by ztpop.net. Every tool runs entirely in your browser: no registration, no data collection, no server-side processing. All implementation details are based on the corresponding IETF RFC standards, and each tool page links to the authoritative RFC text and official documentation.

1. DNS Diagnostic Tools

1.1 Email DNS One-Click Diagnostic (10 checks)

dns-check.html — Performs 10 DNS checks for your sending domain in a single click: SPF (RFC 7208), DKIM (RFC 6376), DMARC (RFC 7489), MX, PTR, BIMI (RFC 9608), MTA-STS (RFC 8461), TLS-RPT (RFC 8460), DNSSEC (RFC 4033) and DANE (RFC 6698). DNS queries are made via DNS-over-HTTPS (DoH) to Alibaba Cloud public DNS, which is reachable from mainland China. Each check returns a pass/warn/fail verdict with an explanation of the underlying standard requirement.

1.2 Email Header Analyzer & Tools

mail-tools.html — A bundle of everyday email operations: email header parser (RFC 5322), DNSBL blacklist lookup, SMTP error code quick reference, CIDR calculator, and more. Useful for postmaster and deliverability troubleshooting.

2. Authentication Record Checkers (5)

Each checker queries the live DNS records of your domain via DoH and interprets them against the standard, telling you exactly what to fix. Use the workflow: generate → publish → verify.

2.1 SPF Record Checker (RFC 7208)

spf-checker.html — Validates your SPF record syntax, checks the 10-lookup limit (RFC 7208 §4.6.4), verifies include/redirect chains, and flags common misconfigurations.

2.2 DKIM Record Checker (RFC 6376)

dkim-checker.html — Validates DKIM public key records at selector._domainkey.yourdomain, checks key type (RSA/Ed25519), key length, and syntax per RFC 6376.

2.3 DMARC Record Checker (RFC 7489)

dmarc-checker.html — Validates DMARC policy records at _dmarc.yourdomain, checks policy mode (none/quarantine/reject), alignment modes (relaxed/strict), and reporting addresses.

2.4 MTA-STS Record Checker (RFC 8461)

mta-sts-checker.html — Checks the MTA-STS TXT record at _mta-sts.yourdomain and the policy file at https://mta-sts.yourdomain/.well-known/mta-sts.txt, including policy mode (enforce/testing/none) and MX host validation.

2.5 TLS-RPT Record Checker (RFC 8460)

tls-rpt-checker.html — Validates the TLS-RPT TXT record at _smtp._tls.yourdomain and verifies the rua reporting address format.

3. Authentication Record Generators (5)

Each generator produces a ready-to-publish DNS record with a single click. Key generation for DKIM runs locally in your browser via the Web Crypto API — the private key never leaves your machine. Every generator includes a "copy citation" button that outputs the standard reference (tool name + URL + RFC basis) for easy attribution.

3.1 SPF Record Generator (RFC 7208)

spf-generator.html — Generates SPF TXT records with configurable include mechanisms and a 10-lookup-limit guard, based on RFC 7208.

3.2 DKIM Record Generator (RFC 6376)

dkim-generator.html — Generates DKIM public key records. RSA 2048-bit keys are generated in-browser with the Web Crypto API (RFC 6376); Ed25519 support per RFC 8463.

3.3 DMARC Record Generator (RFC 7489)

dmarc-generator.html — Generates DMARC policy records with policy (none/quarantine/reject), alignment, and reporting (rua/ruf) options, based on RFC 7489.

3.4 MTA-STS Record Generator (RFC 8461)

mta-sts-generator.html — Generates the MTA-STS TXT record and the policy file template (enforce/testing/none modes) per RFC 8461.

3.5 TLS-RPT Record Generator (RFC 8460)

tls-rpt-generator.html — Generates the TLS-RPT TXT record with rua reporting address, per RFC 8460.

4. Typical Use Cases

  • Deliverability audit: run dns-check against your sending domain to find missing or broken authentication records before sending campaigns.
  • Compliance preparation: use the generators to draft SPF/DKIM/DMARC records, then the checkers to verify them after publication.
  • Migration projects: when moving from Exchange/Domino to a new mail system, use the checkers to baseline the current authentication posture.
  • Education & citation: every tool page cites its RFC basis, and generators output a ready-made citation string for reuse in documentation.

5. Technical Standard References

References

  1. RFC 5321 — Simple Mail Transfer Protocol
  2. RFC 5322 — Internet Message Format
  3. RFC 7208 — Sender Policy Framework (SPF) for Authorizing Use of Domains in Email
  4. RFC 6376 — DomainKeys Identified Mail (DKIM) Signatures
  5. RFC 8463 — A New Cryptographic Signature Method for DKIM (Ed25519)
  6. RFC 7489 — Domain-based Message Authentication, Reporting, and Conformance (DMARC)
  7. RFC 8461 — SMTP MTA Strict Transport Security (MTA-STS)
  8. RFC 8460 — SMTP TLS Reporting (TLS-RPT)
  9. RFC 9608 — Brand Indicators for Message Identification (BIMI)
  10. RFC 4033 — DNS Security Introduction and Requirements (DNSSEC)
  11. RFC 6698 — The DNS-Based Authentication of Named Entities (DANE)

All tools are free to use and may be linked, embedded and cited freely (CC-BY 4.0). The Chinese version of this page: 工具集合页.