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Email Tools

Confirm mail flows and authenticates. Test MX routing and SMTP conversation, validate SPF, DKIM and DMARC alignment, and check whether your sending addresses appear on reputation lists.

How these tools run · MX, SPF, DKIM and DMARC checks query DNS TXT/MX records through Node.js dns.promises; the SPF check walks include/redirect mechanisms recursively and counts the RFC 7208 10-lookup limit; the SMTP Test opens a real SMTP conversation on port 25; the Blacklist Check queries the Spamhaus ZEN DNSBL for each A/MX address.

Tools in this category

MX Lookup

Mail exchangers with priorities and resolved hosts.

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SMTP Test

Full SMTP conversation, banner, TLS and relay check.

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SPF Check

Parse SPF, count lookups and flag syntax problems.

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DKIM Check

Retrieve and validate a selector public key.

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DMARC Check

Policy, alignment and reporting address review.

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Blacklist Check

Query 90+ DNSBLs for an IP or mail domain.

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Related guides

In-depth articles that cover email tools in more detail.

SPF, DKIM, and DMARC Explained for Mail Administrators

Three records, three jobs, one goal: proving your mail is really from you. A practical walkthrough of how they fit together and how to verify each one.

Editorial note

Maintained by the networkutils.org editorial team. Tool descriptions and methodology on this page reflect the live implementation in the NetworkUtils.org backend. Last updated September 2026.