← Frankys Web GitHub Contact

Email diagnostic tools

Live checks of a domain's email configuration: authentication (SPF, DKIM, DMARC, DANE, BIMI), transport security (MTA-STS, TLS-RPT, certificates), MX and DNS, blocklists and the connection to mail servers and mail clients, individually or bundled in the Domain Check. Records and endpoints are resolved, rated and checked for common mistakes. No sign-up, no test mails; only publicly reachable DNS records and services are evaluated.

Overview

Domain Check All email checks for a domain in one run: MX, SPF, DMARC, DKIM, MTA-STS and an SMTP connection test. SMTP Test Connects to a domain's MX servers and checks port 25, EHLO and STARTTLS. Exchange Server Check Check the Exchange build of your OWA URL against Microsoft's build list.

DNS

DNS Lookup Resolve a name or an IP directly in DNS and show the standard records. CAA Check Check a domain's CAA records: which certification authorities may issue. MX Lookup Resolve MX records sorted by priority, with the IP addresses of the mail servers.

Email

Email Header Analyzer Paste a raw email header and read the delivery path with SPF, DKIM and DMARC results. Blocklist Check Check an IP or domain against well-known email blocklists (DNSBL/DBL).

Email authentication

SPF Check Find the SPF record, check its syntax, count DNS lookups against the limit of 10. DMARC Analyzer Read the DMARC record and assess policy, alignment and reporting addresses. DKIM Lookup Query the DKIM public key, check the real key length and the record status. MTA-STS and TLS-RPT Check Check the MTA-STS record and HTTPS policy, MX comparison, certificate, TLS-RPT. DANE Check Check the TLSA records of the MX hosts: DNSSEC, Usage/Selector/Matching, coverage. BIMI Check Check a domain's BIMI record: logo URL, SVG profile, VMC and the DMARC precondition.

TLS & certificates

Certificate Check Check a host's TLS certificate: trust chain, validity, version, cipher.

Client configuration

Autodiscover Check Check Exchange Autodiscover: DNS entries, certificate and an anonymous endpoint test on port 443. Autoconfig Check Check Thunderbird auto-configuration: SRV records, autoconfig XML and the Mozilla ISPDB. IMAP/POP3/SMTP TLS Test Check a mail server host on the client ports 143/993/110/995/587/465: TLS, certificate, capabilities.