Introducing SendSignal Tools
Every email team ends up with the same browser bookmarks: a DNS lookup here, an SPF checker there, a header analyzer somewhere else. We got tired of bouncing between them, so we built SendSignal Tools — one fast, free toolbox for the checks email people run every day.
What's in it
- DNS lookups — A, AAAA, PTR, MX, TXT, NS, CAA and SOA records, with TTLs.
- SPF checker and minimizer — expands every include, counts DNS lookups against the 10-lookup limit, and can flatten an over-limit record into a zero-lookup version.
- DKIM, DMARC and BIMI checkers — fetch a record or paste one, and every tag gets a plain-English explanation instead of a pass/fail black box.
- Blocklist check — your sending IP against the major DNSBLs in parallel, with each list's return codes decoded.
- Header analyzer — paste raw headers to see the delivery path hop by hop, where the delays were, and how the message authenticated.
- Encoding helpers — decode Base64, Quoted-Printable and
=?utf-8?...?=subject lines, and search Unicode glyphs by name.
Built to be shared
Every check that reads from DNS lives at a shareable URL — run a check, copy the address bar, and paste it in a ticket or a Slack thread. Paste-based tools (validators, the decoder, the header analyzer) run in memory and are never stored or logged.
Why we built it
We build SendSignal, an email platform for developers. Deliverability work is our day job, and these are the tools we wanted to exist. If a check surfaces something confusing about your SPF tree or your DMARC policy, that's exactly the kind of thing our platform handles for you.