Free MTA-STS checker / MTA STS checker (MTA-STS monitoring)
MTA-STS / MTA STS check: is _mta-sts still publishing v=STSv1, and does the HTTPS policy at mta-sts./.well-known/mta-sts.txt still load (mode, mx, max_age)? Same signals CrowWake watches hourly — paste-ready scaffold when either half drifts.
Full check / domain monitoring
Domain monitoring pulse — SPF + DKIM + DMARC + MX + SSL + CAA vs live issuer (email auth flock)
SPF / SPF checker
SPF checker — v=spf1 include tree + 10 DNS-lookup limit, missing/+all warn
DKIM / DKIM checker
DKIM checker — common selectors, missing/empty public key warn
DMARC / DMARC checker
DMARC checker — _dmarc v=DMARC1 policy present, p=none warn, spoofing posture
MX / MX checker
MX checker — inbound exchangers present, priorities + hosts
DNS A / DNS A checker
DNS A checker — does the hostname still have an IPv4 A record
Apex checker / apex domain
Apex checker — A/AAAA at the apex domain (zone apex) + CNAME-at-apex warning
CAA record / tester
CAA record checker / CAA tester — allow-list present + does it permit the live TLS issuer
MTA-STS / MTA STS checker
MTA-STS checker / MTA STS checker — DNS id + HTTPS policy (mode, mx, max_age) still live
TLS-RPT / TLS reporting
TLS-RPT checker / TLS reporting — _smtp._tls v=TLSRPTv1 rua still published
BIMI / BIMI checker
BIMI checker — default._bimi v=BIMI1 inbox brand-mark DNS still published
SSL / expired / monitoring
SSL days left or expired + live issuer (pair with CAA)
HTTP status monitoring / website HTTPS
HTTP status monitoring checker — HTTPS status code + title
Expiry / WHOIS monitoring
Domain expiry monitoring — registration runway via public RDAP/WHOIS path
HTTPS redirect / HSTS / X-Frame-Options / X-Content-Type-Options / security headers
HTTPS redirect / HSTS / X-Frame-Options / X-Content-Type-Options / security headers checker — force HTTPS, Strict-Transport-Security, clickjacking, nosniff still live
Open port scanner / open ports checker
Open port scanner — risky FTP, Telnet, MySQL, Postgres, Redis, MongoDB still answering on the public hostname
TTFB / TTFB checker / performance
TTFB checker — Time to First Byte / website performance monitoring pulse still sane
Fail or warn? You’ll get copy-paste DNS examples for this domain. After you start free monitoring, the same fix hints stay on the domain detail page.