Email authentication and publishing tools
Understand public DNS records, examine message evidence, and prepare the small details that go into an email. The toolbox separates authentication records from message verification and delivery, helping you decide what a result actually proves.
11 free tools in this collection
Email list cleaner
Remove duplicate entries, whitespace and obviously malformed addresses.
Open toolDMARC report reader
Upload DMARC XML and inspect sending sources and authentication results.
Open toolEmail header analyzer
Paste raw headers to diagnose routing delays and authentication evidence.
Open toolSPF checker
Inspect a domain's SPF syntax and recursively count DNS-triggering terms.
Open toolDMARC checker
Create a policy record and inspect an existing record's syntax.
Open toolDKIM checker
Check a supplied selector and domain for a usable DKIM DNS record.
Open toolSubject & preheader
Preview supplied newsletter subject and preheader combinations.
Open toolEmail signature
Create a copyable signature with contact links and a layout preview.
Open toolMailto link builder
Create properly encoded email links with recipients, subject and body.
Open toolEmail headers
Transport diagnostics
Inspect records in the right order
Start by identifying the domain and sending services you intend to use. SPF describes authorized envelope senders; DKIM publishes a selector-specific key; DMARC describes alignment with the visible From domain and requested policy. A TXT record check can explain supported syntax and limits. It cannot prove that a service holds the correct private key or that every message will authenticate.
Use headers and reports as evidence
An email header contains routing and authentication claims added by different systems. Treat those claims according to where they were added rather than trusting every line equally. DMARC aggregate XML summarizes receiver observations over a reporting period. Review unfamiliar sending sources against your own service inventory before changing policy, and keep report counts distinct from all mail sent.
Preview the presentation before sending
Subject lines and preheaders can be clipped differently by client, screen width and font. The preview tool uses explicit character budgets rather than pretending to reproduce every inbox. Signature HTML is a copyable starting point that still needs testing in your mail client. A syntax-cleaned address list can remove obvious errors and duplicates, but it cannot confirm mailbox existence or consent.
Common questions
Are live DNS checks private?
Pasted-record checks run locally. Live modes send the domain or selector to Google Public DNS over HTTPS, as disclosed in the tool and privacy page. Network failures are not treated as successful authentication.
Does a passing record mean my mail reaches the inbox?
No. Record syntax and publication are only part of authentication, and authentication is only part of delivery. Message signing, alignment, sending reputation and receiver decisions also matter.