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SendSignal Tools
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Useful tools for email people.

DNS lookups, SPF, DKIM, DMARC and BIMI checks, blocklist status, header forensics and encoding utilities. Free, fast and shareable by URL.

Or start with a DNS lookup or header analysis.

DNS

Look up any record type with TTLs, straight from the resolver.

DNS lookupA, AAAA, PTR, MX, TXT, NS, CAA and SOA records for any name.

Authentication

Check and explain SPF, DKIM, DMARC and BIMI records.

SPF checkerFetch a domain's SPF record, expand every include and count DNS lookups.SPF minimizerFlatten and optimize an SPF record that is over the 10-lookup limit.DKIM checkerFetch a published DKIM key by selector and validate it.DKIM validatorPaste a DKIM record and get every tag explained.DMARC checkerFetch a domain's DMARC policy and verify report destinations.DMARC validatorPaste a DMARC record and get every tag explained.BIMI checkerFetch a BIMI record and check its logo and certificate URLs.

Deliverability

Blocklist status and message forensics.

Blocklist checkCheck an IP or domain against the major DNS blocklists.Header analyzerPaste raw headers for the hop chain, delays and auth verdicts.

Encoding

Decode mail encodings and find Unicode glyphs.

DecoderDecode Base64, Quoted-Printable and RFC 2047 encoded words.Glyph searchFind Unicode characters by name for subject lines.